Page 1
FINAL JEE –MAIN EXAMINATION – APRIL, 2024
(Held On Saturday 06
th
April, 2024) TIME : 9 : 00 AM to 12 : 00 NOON
MATHEMATICS TEST PAPER WITH SOLUTION
SECTION-A
1. If
3
1
x sin , x 0
f(x) = ,then
x
0 , x 0
?? ????
?? ?? ????
???? ?? ?? ?] ?? (1) f ''(0) 1 ?] (2)
2
2 24 –
f ''
2
?? ????
?] ????
???? ????
(3)
2
2 12 –
f ''
2
?? ????
?] ????
???? ????
(4) f ''(0) 0 ?] Ans. (2)
Sol. f'(x) =
2
1 1
3x sin xcos
x x
?? ?? ?? ?? ?M ?? ?? ?? ?? ?? ?? ?? ?? 1
sin
1 1 1 x
f "(x) 6xsin 3cos cos
x x x x
????
????
?? ?? ?? ?? ?? ?? ????
?] ?M ?M ?M ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 2
2 12 24
f "
2 2
?? ?M ?? ????
?] ?M ?] ????
?? ?? ?? ????
2. If A(3,1,–1),
5 7 1
B , ,
3 3 3
????
????
????
, C(2,2,1) and
10 2 –1
D , ,
3 3 3
????
????
????
are the vertices of a quadrilateral
ABCD, then its area is
(1)
4 2
3
(2)
5 2
3
(3) 2 2 (4)
2 2
3
Ans. (1)
Sol.
D
C
B
A
Area =
1
BD AC
2
?? 5 5 2
ˆˆ ˆ
BD i j k
3 3 3
?] ?M ?M ˆˆ ˆ
AC i j 2k ?] ?M ?M 3.
?H ?I /4 2 2
2
3 3
0
cos xsin x
dx
cos x sin x
?? ?K ?? is equal to
(1) 1/12 (2) 1/9
(3) 1/6 (4) 1/3
Ans. (3)
Sol. Divide Nr & Dr by cosx
?H ?I /4 2 2
2
3
0
tan xsec xdx
dx
1 tan x
?? ?K ?? Let 1 + tan
3
x = t
tan
2
x sec
2
x dx =
dt
3
2
2
1
1 dt 1
3 6 t
?] ?? 4. The mean and standard deviation of 20 observations
are found to be 10 and 2, respectively. On
respectively, it was found that an observation by
mistake was taken 8 instead of 12. The correct
standard deviation is
(1) 3.86 (2) 1.8
(3) 3.96 (4) 1.94
Ans. (3)
Sol. Mean (x) 10 ?]
i
x
10
20
?s ???]
?s x
i
= 10×20 = 200
If 8 is replaced by 12, then ?s x
i
= 200 – 8 + 12 = 204
Page 2
FINAL JEE –MAIN EXAMINATION – APRIL, 2024
(Held On Saturday 06
th
April, 2024) TIME : 9 : 00 AM to 12 : 00 NOON
MATHEMATICS TEST PAPER WITH SOLUTION
SECTION-A
1. If
3
1
x sin , x 0
f(x) = ,then
x
0 , x 0
?? ????
?? ?? ????
???? ?? ?? ?] ?? (1) f ''(0) 1 ?] (2)
2
2 24 –
f ''
2
?? ????
?] ????
???? ????
(3)
2
2 12 –
f ''
2
?? ????
?] ????
???? ????
(4) f ''(0) 0 ?] Ans. (2)
Sol. f'(x) =
2
1 1
3x sin xcos
x x
?? ?? ?? ?? ?M ?? ?? ?? ?? ?? ?? ?? ?? 1
sin
1 1 1 x
f "(x) 6xsin 3cos cos
x x x x
????
????
?? ?? ?? ?? ?? ?? ????
?] ?M ?M ?M ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 2
2 12 24
f "
2 2
?? ?M ?? ????
?] ?M ?] ????
?? ?? ?? ????
2. If A(3,1,–1),
5 7 1
B , ,
3 3 3
????
????
????
, C(2,2,1) and
10 2 –1
D , ,
3 3 3
????
????
????
are the vertices of a quadrilateral
ABCD, then its area is
(1)
4 2
3
(2)
5 2
3
(3) 2 2 (4)
2 2
3
Ans. (1)
Sol.
D
C
B
A
Area =
1
BD AC
2
?? 5 5 2
ˆˆ ˆ
BD i j k
3 3 3
?] ?M ?M ˆˆ ˆ
AC i j 2k ?] ?M ?M 3.
?H ?I /4 2 2
2
3 3
0
cos xsin x
dx
cos x sin x
?? ?K ?? is equal to
(1) 1/12 (2) 1/9
(3) 1/6 (4) 1/3
Ans. (3)
Sol. Divide Nr & Dr by cosx
?H ?I /4 2 2
2
3
0
tan xsec xdx
dx
1 tan x
?? ?K ?? Let 1 + tan
3
x = t
tan
2
x sec
2
x dx =
dt
3
2
2
1
1 dt 1
3 6 t
?] ?? 4. The mean and standard deviation of 20 observations
are found to be 10 and 2, respectively. On
respectively, it was found that an observation by
mistake was taken 8 instead of 12. The correct
standard deviation is
(1) 3.86 (2) 1.8
(3) 3.96 (4) 1.94
Ans. (3)
Sol. Mean (x) 10 ?]
i
x
10
20
?s ???]
?s x
i
= 10×20 = 200
If 8 is replaced by 12, then ?s x
i
= 200 – 8 + 12 = 204
?| Correct mean
i
x
(x)
20
?s ?]
204
10.2
20
?]?]
?q Standard deviation = 2
?| Variance = (S.D.)
2
= 2
2
= 4
??
2
2
i i
x x
4
20 20
????
?s?s
?M?]
????
????
????
??
?H ?I 2
2
i
x
10 4
20
?s ?M?]
??
2
i
x
104
20
?s ?]
?? ?s x
i
2
= 2080
Now, replaced '8' observations by '12'
Then,
2 2 2
i
x 2080 8 12 2160 ?s ?] ?M ?K ?]
?| Variance of removing observations
??
2
2
i i
x x
20 20
????
?s?s
?M????
????
????
?? ?@ ?H ?I 2 2160
10.2
20
?M ?@ ?@ ?? ?@ 108 – 104.04
?? 3.96
Correct standard deviation
= 3.96
5. The function
2
2
x 2x – 15
f(x)
x – 4x 9
?K ?] ?K , x?? R is
(1) both one-one and onto.
(2) onto but not one-one.
(3) neither one-one nor onto.
(4) one-one but not onto.
NTA Ans. (3)
Ans. Bonus
Sol.
2
(x 5)(x 3)
f(x)
x 4x 9
?K?M
?] ?M?K
Let g(x) = x
2
– 4x + 9
D < 0
g(x) > 0 for x ?? R
x
?@ f( 5) 0
f(3) 0
?M?] ?? ?| ?? ?] ?? ?@ So, f(x) is many-one.
again,
yx
2
– 4xy + 9y = x
2
+ 2x – 15
x
2
(y – 1) – 2x(2y + 1) + (9y + 15) = 0
for ?B ?@ x ?? R ?? D ?? 0
D = 4(2y + 1)
2
– 4(y –1) (9y + 15) ???@ 0
5y
2
+ 2y + 16 ?? 0
(5y – 8) (y + 2) ?? ?@ 0
–2
8/5
?? ?@ ?? ?@ ??
8
y –2,
5
????
??????
????
range
Note : If function is defined from f : R ?? R then
only correct answer is option (3)
???@ Bonus
6. Let A = {n ?? ?@ [100, 700] ???@ N : n is neither a
multiple of 3 nor a multiple of 4}. Then the
number of elements in A is
(1) 300 (2) 280
(3) 310 (4) 290
Ans. (1)
Sol. n(3) ?? multiple of 3
102, 105, 108, ..... , 699
T
n
= 699 = 102 + (n – 1)(3)
n = 200
n(3) = 200
?q n(4) ?? multiple of 4
Page 3
FINAL JEE –MAIN EXAMINATION – APRIL, 2024
(Held On Saturday 06
th
April, 2024) TIME : 9 : 00 AM to 12 : 00 NOON
MATHEMATICS TEST PAPER WITH SOLUTION
SECTION-A
1. If
3
1
x sin , x 0
f(x) = ,then
x
0 , x 0
?? ????
?? ?? ????
???? ?? ?? ?] ?? (1) f ''(0) 1 ?] (2)
2
2 24 –
f ''
2
?? ????
?] ????
???? ????
(3)
2
2 12 –
f ''
2
?? ????
?] ????
???? ????
(4) f ''(0) 0 ?] Ans. (2)
Sol. f'(x) =
2
1 1
3x sin xcos
x x
?? ?? ?? ?? ?M ?? ?? ?? ?? ?? ?? ?? ?? 1
sin
1 1 1 x
f "(x) 6xsin 3cos cos
x x x x
????
????
?? ?? ?? ?? ?? ?? ????
?] ?M ?M ?M ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 2
2 12 24
f "
2 2
?? ?M ?? ????
?] ?M ?] ????
?? ?? ?? ????
2. If A(3,1,–1),
5 7 1
B , ,
3 3 3
????
????
????
, C(2,2,1) and
10 2 –1
D , ,
3 3 3
????
????
????
are the vertices of a quadrilateral
ABCD, then its area is
(1)
4 2
3
(2)
5 2
3
(3) 2 2 (4)
2 2
3
Ans. (1)
Sol.
D
C
B
A
Area =
1
BD AC
2
?? 5 5 2
ˆˆ ˆ
BD i j k
3 3 3
?] ?M ?M ˆˆ ˆ
AC i j 2k ?] ?M ?M 3.
?H ?I /4 2 2
2
3 3
0
cos xsin x
dx
cos x sin x
?? ?K ?? is equal to
(1) 1/12 (2) 1/9
(3) 1/6 (4) 1/3
Ans. (3)
Sol. Divide Nr & Dr by cosx
?H ?I /4 2 2
2
3
0
tan xsec xdx
dx
1 tan x
?? ?K ?? Let 1 + tan
3
x = t
tan
2
x sec
2
x dx =
dt
3
2
2
1
1 dt 1
3 6 t
?] ?? 4. The mean and standard deviation of 20 observations
are found to be 10 and 2, respectively. On
respectively, it was found that an observation by
mistake was taken 8 instead of 12. The correct
standard deviation is
(1) 3.86 (2) 1.8
(3) 3.96 (4) 1.94
Ans. (3)
Sol. Mean (x) 10 ?]
i
x
10
20
?s ???]
?s x
i
= 10×20 = 200
If 8 is replaced by 12, then ?s x
i
= 200 – 8 + 12 = 204
?| Correct mean
i
x
(x)
20
?s ?]
204
10.2
20
?]?]
?q Standard deviation = 2
?| Variance = (S.D.)
2
= 2
2
= 4
??
2
2
i i
x x
4
20 20
????
?s?s
?M?]
????
????
????
??
?H ?I 2
2
i
x
10 4
20
?s ?M?]
??
2
i
x
104
20
?s ?]
?? ?s x
i
2
= 2080
Now, replaced '8' observations by '12'
Then,
2 2 2
i
x 2080 8 12 2160 ?s ?] ?M ?K ?]
?| Variance of removing observations
??
2
2
i i
x x
20 20
????
?s?s
?M????
????
????
?? ?@ ?H ?I 2 2160
10.2
20
?M ?@ ?@ ?? ?@ 108 – 104.04
?? 3.96
Correct standard deviation
= 3.96
5. The function
2
2
x 2x – 15
f(x)
x – 4x 9
?K ?] ?K , x?? R is
(1) both one-one and onto.
(2) onto but not one-one.
(3) neither one-one nor onto.
(4) one-one but not onto.
NTA Ans. (3)
Ans. Bonus
Sol.
2
(x 5)(x 3)
f(x)
x 4x 9
?K?M
?] ?M?K
Let g(x) = x
2
– 4x + 9
D < 0
g(x) > 0 for x ?? R
x
?@ f( 5) 0
f(3) 0
?M?] ?? ?| ?? ?] ?? ?@ So, f(x) is many-one.
again,
yx
2
– 4xy + 9y = x
2
+ 2x – 15
x
2
(y – 1) – 2x(2y + 1) + (9y + 15) = 0
for ?B ?@ x ?? R ?? D ?? 0
D = 4(2y + 1)
2
– 4(y –1) (9y + 15) ???@ 0
5y
2
+ 2y + 16 ?? 0
(5y – 8) (y + 2) ?? ?@ 0
–2
8/5
?? ?@ ?? ?@ ??
8
y –2,
5
????
??????
????
range
Note : If function is defined from f : R ?? R then
only correct answer is option (3)
???@ Bonus
6. Let A = {n ?? ?@ [100, 700] ???@ N : n is neither a
multiple of 3 nor a multiple of 4}. Then the
number of elements in A is
(1) 300 (2) 280
(3) 310 (4) 290
Ans. (1)
Sol. n(3) ?? multiple of 3
102, 105, 108, ..... , 699
T
n
= 699 = 102 + (n – 1)(3)
n = 200
n(3) = 200
?q n(4) ?? multiple of 4
100, 104, 108, ...., 700
T
n
= 700 = 100 + (n – 1) (4)
n = 151
n(4) = 151
n(3 ?? 4) ?? multiple of 3 & 4 both
108, 120, 132, ....., 696
T
n
= 696 = 108 + (n – 1)(12)
n = 50
n(3 ?? ?@ 4) = 50
n(3 ???@ 4) = n(3) + n(4) – n(3 ?? ?@ 4)
= 200 + 151 – 50
= 301
?H ?I n 3 4 ?? = Total – n(3 ?? ?@ 4) = neither a multiple
of 3 nor a multiple of 4
= 601 – 301 = 300
7. Let C be the circle of minimum area touching the
parabola y = 6 – x
2
and the lines y = 3 x . Then,
which one of the following points lies on the circle
C ?
(1) (2, 4) (2) (1, 2)
(3) (2, 2) (4) (1, 1)
Ans. (1)
Sol.
(0,6)
(0,6–r)
Equation of circle
x
2
+ (y – (6 – r))
2
= r
2
touches 3 x y 0 ?M?]
p = r
0 (6 r)
r
2
?M?M
?]
|r – 6| = 2r
r = 2
?| Circle x
2
+ (y – 4)
2
= 4
(2, 4) Satisfies this equation
8. For ?? , ?? ?? R and a natural number n, let
2
2
r
n
r 1
2
A 2r 2 n –
n(3n – 1)
3r – 2 3
2
?K??
?]?? . Then 2A
10
– A
8
is
(1) 4 ?? + 2 ?? (2) 2 ?? + 4 ??
(3) 2n (4) 0
Ans. (1)
Sol.
2
2
r
n
r 1
2
A 2r 2 n –
n(3n – 1)
3r – 2 3
2
?K??
?]??
2
2
10 8
n
20 1
2
2A – A 40 2 n –
n(3n – 1)
56 3
2
?K??
?]??
?H ?I 2
2
n
8 1
2
– 16 2 n –
n 3n – 1
22 3
2
?K??
??
?H ?I 2
2
n
12 1
2
24 2 n –
n 3n – 1
34 3
2
?K??
????
2
2
n
0 1
2
0 2 n –
n(3n – 1)
–2 3
2
?K??
????
?H ?I ?H ?I 2 2
– 2 (n – ) – n 2 ?? ?? ?K ??
– 2(– – 2 ) ?? ?? ?? 4 2 ?? ?? ?K ??
Page 4
FINAL JEE –MAIN EXAMINATION – APRIL, 2024
(Held On Saturday 06
th
April, 2024) TIME : 9 : 00 AM to 12 : 00 NOON
MATHEMATICS TEST PAPER WITH SOLUTION
SECTION-A
1. If
3
1
x sin , x 0
f(x) = ,then
x
0 , x 0
?? ????
?? ?? ????
???? ?? ?? ?] ?? (1) f ''(0) 1 ?] (2)
2
2 24 –
f ''
2
?? ????
?] ????
???? ????
(3)
2
2 12 –
f ''
2
?? ????
?] ????
???? ????
(4) f ''(0) 0 ?] Ans. (2)
Sol. f'(x) =
2
1 1
3x sin xcos
x x
?? ?? ?? ?? ?M ?? ?? ?? ?? ?? ?? ?? ?? 1
sin
1 1 1 x
f "(x) 6xsin 3cos cos
x x x x
????
????
?? ?? ?? ?? ?? ?? ????
?] ?M ?M ?M ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 2
2 12 24
f "
2 2
?? ?M ?? ????
?] ?M ?] ????
?? ?? ?? ????
2. If A(3,1,–1),
5 7 1
B , ,
3 3 3
????
????
????
, C(2,2,1) and
10 2 –1
D , ,
3 3 3
????
????
????
are the vertices of a quadrilateral
ABCD, then its area is
(1)
4 2
3
(2)
5 2
3
(3) 2 2 (4)
2 2
3
Ans. (1)
Sol.
D
C
B
A
Area =
1
BD AC
2
?? 5 5 2
ˆˆ ˆ
BD i j k
3 3 3
?] ?M ?M ˆˆ ˆ
AC i j 2k ?] ?M ?M 3.
?H ?I /4 2 2
2
3 3
0
cos xsin x
dx
cos x sin x
?? ?K ?? is equal to
(1) 1/12 (2) 1/9
(3) 1/6 (4) 1/3
Ans. (3)
Sol. Divide Nr & Dr by cosx
?H ?I /4 2 2
2
3
0
tan xsec xdx
dx
1 tan x
?? ?K ?? Let 1 + tan
3
x = t
tan
2
x sec
2
x dx =
dt
3
2
2
1
1 dt 1
3 6 t
?] ?? 4. The mean and standard deviation of 20 observations
are found to be 10 and 2, respectively. On
respectively, it was found that an observation by
mistake was taken 8 instead of 12. The correct
standard deviation is
(1) 3.86 (2) 1.8
(3) 3.96 (4) 1.94
Ans. (3)
Sol. Mean (x) 10 ?]
i
x
10
20
?s ???]
?s x
i
= 10×20 = 200
If 8 is replaced by 12, then ?s x
i
= 200 – 8 + 12 = 204
?| Correct mean
i
x
(x)
20
?s ?]
204
10.2
20
?]?]
?q Standard deviation = 2
?| Variance = (S.D.)
2
= 2
2
= 4
??
2
2
i i
x x
4
20 20
????
?s?s
?M?]
????
????
????
??
?H ?I 2
2
i
x
10 4
20
?s ?M?]
??
2
i
x
104
20
?s ?]
?? ?s x
i
2
= 2080
Now, replaced '8' observations by '12'
Then,
2 2 2
i
x 2080 8 12 2160 ?s ?] ?M ?K ?]
?| Variance of removing observations
??
2
2
i i
x x
20 20
????
?s?s
?M????
????
????
?? ?@ ?H ?I 2 2160
10.2
20
?M ?@ ?@ ?? ?@ 108 – 104.04
?? 3.96
Correct standard deviation
= 3.96
5. The function
2
2
x 2x – 15
f(x)
x – 4x 9
?K ?] ?K , x?? R is
(1) both one-one and onto.
(2) onto but not one-one.
(3) neither one-one nor onto.
(4) one-one but not onto.
NTA Ans. (3)
Ans. Bonus
Sol.
2
(x 5)(x 3)
f(x)
x 4x 9
?K?M
?] ?M?K
Let g(x) = x
2
– 4x + 9
D < 0
g(x) > 0 for x ?? R
x
?@ f( 5) 0
f(3) 0
?M?] ?? ?| ?? ?] ?? ?@ So, f(x) is many-one.
again,
yx
2
– 4xy + 9y = x
2
+ 2x – 15
x
2
(y – 1) – 2x(2y + 1) + (9y + 15) = 0
for ?B ?@ x ?? R ?? D ?? 0
D = 4(2y + 1)
2
– 4(y –1) (9y + 15) ???@ 0
5y
2
+ 2y + 16 ?? 0
(5y – 8) (y + 2) ?? ?@ 0
–2
8/5
?? ?@ ?? ?@ ??
8
y –2,
5
????
??????
????
range
Note : If function is defined from f : R ?? R then
only correct answer is option (3)
???@ Bonus
6. Let A = {n ?? ?@ [100, 700] ???@ N : n is neither a
multiple of 3 nor a multiple of 4}. Then the
number of elements in A is
(1) 300 (2) 280
(3) 310 (4) 290
Ans. (1)
Sol. n(3) ?? multiple of 3
102, 105, 108, ..... , 699
T
n
= 699 = 102 + (n – 1)(3)
n = 200
n(3) = 200
?q n(4) ?? multiple of 4
100, 104, 108, ...., 700
T
n
= 700 = 100 + (n – 1) (4)
n = 151
n(4) = 151
n(3 ?? 4) ?? multiple of 3 & 4 both
108, 120, 132, ....., 696
T
n
= 696 = 108 + (n – 1)(12)
n = 50
n(3 ?? ?@ 4) = 50
n(3 ???@ 4) = n(3) + n(4) – n(3 ?? ?@ 4)
= 200 + 151 – 50
= 301
?H ?I n 3 4 ?? = Total – n(3 ?? ?@ 4) = neither a multiple
of 3 nor a multiple of 4
= 601 – 301 = 300
7. Let C be the circle of minimum area touching the
parabola y = 6 – x
2
and the lines y = 3 x . Then,
which one of the following points lies on the circle
C ?
(1) (2, 4) (2) (1, 2)
(3) (2, 2) (4) (1, 1)
Ans. (1)
Sol.
(0,6)
(0,6–r)
Equation of circle
x
2
+ (y – (6 – r))
2
= r
2
touches 3 x y 0 ?M?]
p = r
0 (6 r)
r
2
?M?M
?]
|r – 6| = 2r
r = 2
?| Circle x
2
+ (y – 4)
2
= 4
(2, 4) Satisfies this equation
8. For ?? , ?? ?? R and a natural number n, let
2
2
r
n
r 1
2
A 2r 2 n –
n(3n – 1)
3r – 2 3
2
?K??
?]?? . Then 2A
10
– A
8
is
(1) 4 ?? + 2 ?? (2) 2 ?? + 4 ??
(3) 2n (4) 0
Ans. (1)
Sol.
2
2
r
n
r 1
2
A 2r 2 n –
n(3n – 1)
3r – 2 3
2
?K??
?]??
2
2
10 8
n
20 1
2
2A – A 40 2 n –
n(3n – 1)
56 3
2
?K??
?]??
?H ?I 2
2
n
8 1
2
– 16 2 n –
n 3n – 1
22 3
2
?K??
??
?H ?I 2
2
n
12 1
2
24 2 n –
n 3n – 1
34 3
2
?K??
????
2
2
n
0 1
2
0 2 n –
n(3n – 1)
–2 3
2
?K??
????
?H ?I ?H ?I 2 2
– 2 (n – ) – n 2 ?? ?? ?K ??
– 2(– – 2 ) ?? ?? ?? 4 2 ?? ?? ?K ??
9. The shortest distance between the lines
x – 3 y 15 z – 9
2 –7 5
?K ?]?] and
x 1 y –1 z – 9
2 1 –3
?K ?]?] is
(1) 6 3 (2) 4 3
(3) 5 3 (4) 8 3
Ans. (2)
Sol.
x – 3 y 15 z – 9
2 –7 5
?K ?]?] &
x 1 y –1 z – 9
2 1 –3
?K ?]?]
S.D =
?H ?I ?H ?I 2 1 1 2
1 2
a .a . b .b
b b ??
a
1
= 3, –15, 9 b
1
= 2, –7, 5
a
2
= –1, 1, 9 b
2
= 2, 1, –3
a
2
– a
1
= –4, 16, 0
1 2
ˆˆ ˆ
i j k
ˆˆ ˆ
b b 2 7 5 i(16) j( 16) k(16)
2 1 3
?? ?] ?M ?] ?M ?M ?K ?M
ˆˆ ˆ
16(i j k) ?K?K
1 2
b b 16 3 ???]
?| ?H ?I ?H ?I ?{ ?} 2 1 1 2
a a . b b 16 4 16 (16)(12) ?M ?M ?] ?M ?K ?]
S.D. =
(16)(12)
4 3
16 3
?]
10. A company has two plants A and B to manufacture
motorcycles. 60% motorcycles are manufactured
at plant A and the remaining are manufactured at
plant B. 80% of the motorcycles manufactured at
plant A are rated of the standard quality, while
90% of the motorcycles manufactured at plant B
are rated of the standard quality. A motorcycle
picked up randomly from the total production is
found to be of the standard quality. If p is the
probability that it was manufactured at plant B,
then 126p is
(1) 54 (2) 64
(3) 66 (4) 56
Ans. (1)
Sol.
A B
Manufactured 60% 40%
Standard quality 80% 90%
P(Manufactured at B / found standard quality) = ?
A : Found S.Q
B : Manufacture B
C : Manufacture A
P(E
1
) =
40
100
P(E
2
) =
60
100
P(A/E
1
) =
90
100
P(A/E
2
) =
80
100
P(E
1
/A) =
?H ?I ?H ?I ?H ?I ?H ?I ?H ?I ?H ?I 1 1
1 1 2 2
P A / E P E
P A / E P E P A / E P E ?K 3
7
?]
?| ?@ 126 P = 54
11. Let, ?? , ?? be the distinct roots of the equation
?H ?I 2 2
x – t – 5t 6 x 1 0, ?K ?K ?] t ?? R and a
n
= ?? n
+ ?? n
.
Then the minimum value of
2023 2025
2024
a a
a
?K is
(1) 1/4 (2) –1/2
(3) –1/4 (4) 1/2
Ans. (3)
Sol. by newton's theorem
a
n+2
– (t
2
– 5t + 6)a
n+1
+ a
n
= 0
?| ?@ a
2025
+ a
2023
= (t
2
– 5t + 6) a
2024
?| ?@
2 2025 2023
2024
a a
t 5t 6
a
?K ?] ?M ?K
2
2
1 5
t 5t 6 t
4 2
????
?M ?K ?] ?M ?M????
????
?@ ?| ?@ minimum value =
1
4
?M
Page 5
FINAL JEE –MAIN EXAMINATION – APRIL, 2024
(Held On Saturday 06
th
April, 2024) TIME : 9 : 00 AM to 12 : 00 NOON
MATHEMATICS TEST PAPER WITH SOLUTION
SECTION-A
1. If
3
1
x sin , x 0
f(x) = ,then
x
0 , x 0
?? ????
?? ?? ????
???? ?? ?? ?] ?? (1) f ''(0) 1 ?] (2)
2
2 24 –
f ''
2
?? ????
?] ????
???? ????
(3)
2
2 12 –
f ''
2
?? ????
?] ????
???? ????
(4) f ''(0) 0 ?] Ans. (2)
Sol. f'(x) =
2
1 1
3x sin xcos
x x
?? ?? ?? ?? ?M ?? ?? ?? ?? ?? ?? ?? ?? 1
sin
1 1 1 x
f "(x) 6xsin 3cos cos
x x x x
????
????
?? ?? ?? ?? ?? ?? ????
?] ?M ?M ?M ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 2
2 12 24
f "
2 2
?? ?M ?? ????
?] ?M ?] ????
?? ?? ?? ????
2. If A(3,1,–1),
5 7 1
B , ,
3 3 3
????
????
????
, C(2,2,1) and
10 2 –1
D , ,
3 3 3
????
????
????
are the vertices of a quadrilateral
ABCD, then its area is
(1)
4 2
3
(2)
5 2
3
(3) 2 2 (4)
2 2
3
Ans. (1)
Sol.
D
C
B
A
Area =
1
BD AC
2
?? 5 5 2
ˆˆ ˆ
BD i j k
3 3 3
?] ?M ?M ˆˆ ˆ
AC i j 2k ?] ?M ?M 3.
?H ?I /4 2 2
2
3 3
0
cos xsin x
dx
cos x sin x
?? ?K ?? is equal to
(1) 1/12 (2) 1/9
(3) 1/6 (4) 1/3
Ans. (3)
Sol. Divide Nr & Dr by cosx
?H ?I /4 2 2
2
3
0
tan xsec xdx
dx
1 tan x
?? ?K ?? Let 1 + tan
3
x = t
tan
2
x sec
2
x dx =
dt
3
2
2
1
1 dt 1
3 6 t
?] ?? 4. The mean and standard deviation of 20 observations
are found to be 10 and 2, respectively. On
respectively, it was found that an observation by
mistake was taken 8 instead of 12. The correct
standard deviation is
(1) 3.86 (2) 1.8
(3) 3.96 (4) 1.94
Ans. (3)
Sol. Mean (x) 10 ?]
i
x
10
20
?s ???]
?s x
i
= 10×20 = 200
If 8 is replaced by 12, then ?s x
i
= 200 – 8 + 12 = 204
?| Correct mean
i
x
(x)
20
?s ?]
204
10.2
20
?]?]
?q Standard deviation = 2
?| Variance = (S.D.)
2
= 2
2
= 4
??
2
2
i i
x x
4
20 20
????
?s?s
?M?]
????
????
????
??
?H ?I 2
2
i
x
10 4
20
?s ?M?]
??
2
i
x
104
20
?s ?]
?? ?s x
i
2
= 2080
Now, replaced '8' observations by '12'
Then,
2 2 2
i
x 2080 8 12 2160 ?s ?] ?M ?K ?]
?| Variance of removing observations
??
2
2
i i
x x
20 20
????
?s?s
?M????
????
????
?? ?@ ?H ?I 2 2160
10.2
20
?M ?@ ?@ ?? ?@ 108 – 104.04
?? 3.96
Correct standard deviation
= 3.96
5. The function
2
2
x 2x – 15
f(x)
x – 4x 9
?K ?] ?K , x?? R is
(1) both one-one and onto.
(2) onto but not one-one.
(3) neither one-one nor onto.
(4) one-one but not onto.
NTA Ans. (3)
Ans. Bonus
Sol.
2
(x 5)(x 3)
f(x)
x 4x 9
?K?M
?] ?M?K
Let g(x) = x
2
– 4x + 9
D < 0
g(x) > 0 for x ?? R
x
?@ f( 5) 0
f(3) 0
?M?] ?? ?| ?? ?] ?? ?@ So, f(x) is many-one.
again,
yx
2
– 4xy + 9y = x
2
+ 2x – 15
x
2
(y – 1) – 2x(2y + 1) + (9y + 15) = 0
for ?B ?@ x ?? R ?? D ?? 0
D = 4(2y + 1)
2
– 4(y –1) (9y + 15) ???@ 0
5y
2
+ 2y + 16 ?? 0
(5y – 8) (y + 2) ?? ?@ 0
–2
8/5
?? ?@ ?? ?@ ??
8
y –2,
5
????
??????
????
range
Note : If function is defined from f : R ?? R then
only correct answer is option (3)
???@ Bonus
6. Let A = {n ?? ?@ [100, 700] ???@ N : n is neither a
multiple of 3 nor a multiple of 4}. Then the
number of elements in A is
(1) 300 (2) 280
(3) 310 (4) 290
Ans. (1)
Sol. n(3) ?? multiple of 3
102, 105, 108, ..... , 699
T
n
= 699 = 102 + (n – 1)(3)
n = 200
n(3) = 200
?q n(4) ?? multiple of 4
100, 104, 108, ...., 700
T
n
= 700 = 100 + (n – 1) (4)
n = 151
n(4) = 151
n(3 ?? 4) ?? multiple of 3 & 4 both
108, 120, 132, ....., 696
T
n
= 696 = 108 + (n – 1)(12)
n = 50
n(3 ?? ?@ 4) = 50
n(3 ???@ 4) = n(3) + n(4) – n(3 ?? ?@ 4)
= 200 + 151 – 50
= 301
?H ?I n 3 4 ?? = Total – n(3 ?? ?@ 4) = neither a multiple
of 3 nor a multiple of 4
= 601 – 301 = 300
7. Let C be the circle of minimum area touching the
parabola y = 6 – x
2
and the lines y = 3 x . Then,
which one of the following points lies on the circle
C ?
(1) (2, 4) (2) (1, 2)
(3) (2, 2) (4) (1, 1)
Ans. (1)
Sol.
(0,6)
(0,6–r)
Equation of circle
x
2
+ (y – (6 – r))
2
= r
2
touches 3 x y 0 ?M?]
p = r
0 (6 r)
r
2
?M?M
?]
|r – 6| = 2r
r = 2
?| Circle x
2
+ (y – 4)
2
= 4
(2, 4) Satisfies this equation
8. For ?? , ?? ?? R and a natural number n, let
2
2
r
n
r 1
2
A 2r 2 n –
n(3n – 1)
3r – 2 3
2
?K??
?]?? . Then 2A
10
– A
8
is
(1) 4 ?? + 2 ?? (2) 2 ?? + 4 ??
(3) 2n (4) 0
Ans. (1)
Sol.
2
2
r
n
r 1
2
A 2r 2 n –
n(3n – 1)
3r – 2 3
2
?K??
?]??
2
2
10 8
n
20 1
2
2A – A 40 2 n –
n(3n – 1)
56 3
2
?K??
?]??
?H ?I 2
2
n
8 1
2
– 16 2 n –
n 3n – 1
22 3
2
?K??
??
?H ?I 2
2
n
12 1
2
24 2 n –
n 3n – 1
34 3
2
?K??
????
2
2
n
0 1
2
0 2 n –
n(3n – 1)
–2 3
2
?K??
????
?H ?I ?H ?I 2 2
– 2 (n – ) – n 2 ?? ?? ?K ??
– 2(– – 2 ) ?? ?? ?? 4 2 ?? ?? ?K ??
9. The shortest distance between the lines
x – 3 y 15 z – 9
2 –7 5
?K ?]?] and
x 1 y –1 z – 9
2 1 –3
?K ?]?] is
(1) 6 3 (2) 4 3
(3) 5 3 (4) 8 3
Ans. (2)
Sol.
x – 3 y 15 z – 9
2 –7 5
?K ?]?] &
x 1 y –1 z – 9
2 1 –3
?K ?]?]
S.D =
?H ?I ?H ?I 2 1 1 2
1 2
a .a . b .b
b b ??
a
1
= 3, –15, 9 b
1
= 2, –7, 5
a
2
= –1, 1, 9 b
2
= 2, 1, –3
a
2
– a
1
= –4, 16, 0
1 2
ˆˆ ˆ
i j k
ˆˆ ˆ
b b 2 7 5 i(16) j( 16) k(16)
2 1 3
?? ?] ?M ?] ?M ?M ?K ?M
ˆˆ ˆ
16(i j k) ?K?K
1 2
b b 16 3 ???]
?| ?H ?I ?H ?I ?{ ?} 2 1 1 2
a a . b b 16 4 16 (16)(12) ?M ?M ?] ?M ?K ?]
S.D. =
(16)(12)
4 3
16 3
?]
10. A company has two plants A and B to manufacture
motorcycles. 60% motorcycles are manufactured
at plant A and the remaining are manufactured at
plant B. 80% of the motorcycles manufactured at
plant A are rated of the standard quality, while
90% of the motorcycles manufactured at plant B
are rated of the standard quality. A motorcycle
picked up randomly from the total production is
found to be of the standard quality. If p is the
probability that it was manufactured at plant B,
then 126p is
(1) 54 (2) 64
(3) 66 (4) 56
Ans. (1)
Sol.
A B
Manufactured 60% 40%
Standard quality 80% 90%
P(Manufactured at B / found standard quality) = ?
A : Found S.Q
B : Manufacture B
C : Manufacture A
P(E
1
) =
40
100
P(E
2
) =
60
100
P(A/E
1
) =
90
100
P(A/E
2
) =
80
100
P(E
1
/A) =
?H ?I ?H ?I ?H ?I ?H ?I ?H ?I ?H ?I 1 1
1 1 2 2
P A / E P E
P A / E P E P A / E P E ?K 3
7
?]
?| ?@ 126 P = 54
11. Let, ?? , ?? be the distinct roots of the equation
?H ?I 2 2
x – t – 5t 6 x 1 0, ?K ?K ?] t ?? R and a
n
= ?? n
+ ?? n
.
Then the minimum value of
2023 2025
2024
a a
a
?K is
(1) 1/4 (2) –1/2
(3) –1/4 (4) 1/2
Ans. (3)
Sol. by newton's theorem
a
n+2
– (t
2
– 5t + 6)a
n+1
+ a
n
= 0
?| ?@ a
2025
+ a
2023
= (t
2
– 5t + 6) a
2024
?| ?@
2 2025 2023
2024
a a
t 5t 6
a
?K ?] ?M ?K
2
2
1 5
t 5t 6 t
4 2
????
?M ?K ?] ?M ?M????
????
?@ ?| ?@ minimum value =
1
4
?M
12. Let the relations R
1
and R
2
on the set
X = {1, 2, 3, ..., 20} be given by
R
1
= {(x, y) : 2x – 3y = 2} and
R
2
= {(x, y) : –5x + 4y = 0}. If M and N be the
minimum number of elements required to be added
in R
1
and R
2
, respectively, in order to make the
relations symmetric, then M + N equals
(1) 8 (2) 16
(3) 12 (4) 10
Ans. (4)
Sol. x = {1, 2, 3, .......20}
R
1
= {(x, y) : 2x – 3y = 2}
R
2
= {(x, y) : –5x + 4y = 0}
R
1
= {(4, 2), (7, 4), (10, 6), (13, 8), (16, 10), (19, 12)}
R
2
= {(4, 5), (8, 10), (12, 15), (16, 20)}
in R
1
6 element needed
in R
2
4 element needed
So, total 6+4 = 10 element
13. Let a variable line of slope m > 0 passing through
the point (4, –9) intersect the coordinate axes at the
points A and B. the minimum value of the sum of
the distances of A and B from the origin is
(1) 25 (2) 30
(3) 15 (4) 10
Ans. (1)
Sol. equation of line is
y + 9 = m (x – 4)
?|
9 4m
A ,0
m
?K????
?]????
????
B = (0, – 9 – 4m)
?| OA + OB =
9 4m
9 4m
m
?K ?K?K
m 0 ?^
9
13 4m
m
?] ?K ?K
9
4m
9
m
36 4m 12
2 m
?K ?? ?? ?K ??
?| OA + OB ?? 25
14. The interval in which the function f(x) = x
x
, x > 0,
is strictly increasing is
(1)
1
0,
e
????
?? ?? ????
(2)
2
1
,1
e
????
?? ??????
(3) (0, ?? ) (4)
1
,
e
????
?? ?? ??????
Ans. (4)
Sol. f(x) = x
x
; x > 0
?? ny = x ?? nx
1 dy x
nx
y dx x
?]?K
x
dy
x (1 nx)
dx
?]?K
for strictly increasing
dy
0
dx
?? ?? ?@ x
x
(1 + ?? nx) ?? 0
?? ?@ ?? nx ?? –1
x ?? e
–1
x ??
1
e
1
x ,
e
????
????
?? ??????
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