Page 1
CBSE XI | Mathematics
Sample Paper – 2 Solution
CBSE Board
Class XI Mathematics
Sample Paper – 2 Solution
SECTION – A
1. The sum of the infinite series will be:
2 3 4
1 1 1 1
...
3
3 3 3
? ? ? ?
=
1
1
3
1
2
1
3
?
?
OR
23
0.5 0.5555...
0.5 0.05 0.005 ...
5 5 5
...
10
10 10
5
10
1
1
10
5
9
?
? ? ? ? ?
? ? ? ? ?
?
?
?
2. Since A and B are disjoint sets, so their intersection is an empty or a null set. So the
statement is true.
3. cos cos sin sin
4 4 4 4
? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
cos
44
cos ( )
2
sin( )
?? ?? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ??
? ? ? ? ??
???
? ? ? ? ?
??
??
? ? ? ?
Page 2
CBSE XI | Mathematics
Sample Paper – 2 Solution
CBSE Board
Class XI Mathematics
Sample Paper – 2 Solution
SECTION – A
1. The sum of the infinite series will be:
2 3 4
1 1 1 1
...
3
3 3 3
? ? ? ?
=
1
1
3
1
2
1
3
?
?
OR
23
0.5 0.5555...
0.5 0.05 0.005 ...
5 5 5
...
10
10 10
5
10
1
1
10
5
9
?
? ? ? ? ?
? ? ? ? ?
?
?
?
2. Since A and B are disjoint sets, so their intersection is an empty or a null set. So the
statement is true.
3. cos cos sin sin
4 4 4 4
? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
cos
44
cos ( )
2
sin( )
?? ?? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ??
? ? ? ? ??
???
? ? ? ? ?
??
??
? ? ? ?
CBSE XI | Mathematics
Sample Paper – 2 Solution
4.
? ? ? ?
22
1 1 1 i 1 i 1 i 1 1
i
1 i 1 i 1 i 1 1 2 2
1i
???
? ? ? ? ? ?
? ? ? ?
?
1 1 1
11
Comparing with x iy, x ,y
22
1
y
2
Argument = tan tan tan 1
1
x4
2
? ? ?
? ? ?
??
??
?
? ? ? ? ?
??
??
??
SECTION – B
5.
22
4x + y = 100
22
2 2 2 2
xy
1
25 100
b 100,a 25;c b a 100 25 75 5 3
c 5 3 3
eccentricity,e
b 10 2
? ? ?
? ? ? ? ? ? ? ? ?
? ? ?
6. Probability of both the friends not having the same birthday is
365 364
365 365
?
So the probability of two friends having the same birthday is
365 364 364 1
= 1 1 1
365 365 365 365
? ? ? ? ? ?
OR
Let A be the event that the patient will have his teeth cleaned and B be the event that he
will have cavity filled.
P(A) = 0.44, P(B) = 0.24, P(A ? B) = 0.60
P(A n B) = P(A) + P(B) – P(A ? B)
= 0.44 + 0.24 – 0.60
= 0.08
7. Let the four parts be a - 2d, a - d, a + d, a + 2d
So a - 2d + a - d + a + d + a + 2d = 20
a = 5
22
22
[(a 2d)(a 2d)] 2
[(a d)(a d)] 3
(a 4d ) 2
3
(a d )
??
?
??
?
?
?
3a
2
- 12d
2
= 2a
2
- 2d
2
a
2
- 10 d
2
= 0
So, 25=10 d
2
5
d
10
?
?
Page 3
CBSE XI | Mathematics
Sample Paper – 2 Solution
CBSE Board
Class XI Mathematics
Sample Paper – 2 Solution
SECTION – A
1. The sum of the infinite series will be:
2 3 4
1 1 1 1
...
3
3 3 3
? ? ? ?
=
1
1
3
1
2
1
3
?
?
OR
23
0.5 0.5555...
0.5 0.05 0.005 ...
5 5 5
...
10
10 10
5
10
1
1
10
5
9
?
? ? ? ? ?
? ? ? ? ?
?
?
?
2. Since A and B are disjoint sets, so their intersection is an empty or a null set. So the
statement is true.
3. cos cos sin sin
4 4 4 4
? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
cos
44
cos ( )
2
sin( )
?? ?? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ??
? ? ? ? ??
???
? ? ? ? ?
??
??
? ? ? ?
CBSE XI | Mathematics
Sample Paper – 2 Solution
4.
? ? ? ?
22
1 1 1 i 1 i 1 i 1 1
i
1 i 1 i 1 i 1 1 2 2
1i
???
? ? ? ? ? ?
? ? ? ?
?
1 1 1
11
Comparing with x iy, x ,y
22
1
y
2
Argument = tan tan tan 1
1
x4
2
? ? ?
? ? ?
??
??
?
? ? ? ? ?
??
??
??
SECTION – B
5.
22
4x + y = 100
22
2 2 2 2
xy
1
25 100
b 100,a 25;c b a 100 25 75 5 3
c 5 3 3
eccentricity,e
b 10 2
? ? ?
? ? ? ? ? ? ? ? ?
? ? ?
6. Probability of both the friends not having the same birthday is
365 364
365 365
?
So the probability of two friends having the same birthday is
365 364 364 1
= 1 1 1
365 365 365 365
? ? ? ? ? ?
OR
Let A be the event that the patient will have his teeth cleaned and B be the event that he
will have cavity filled.
P(A) = 0.44, P(B) = 0.24, P(A ? B) = 0.60
P(A n B) = P(A) + P(B) – P(A ? B)
= 0.44 + 0.24 – 0.60
= 0.08
7. Let the four parts be a - 2d, a - d, a + d, a + 2d
So a - 2d + a - d + a + d + a + 2d = 20
a = 5
22
22
[(a 2d)(a 2d)] 2
[(a d)(a d)] 3
(a 4d ) 2
3
(a d )
??
?
??
?
?
?
3a
2
- 12d
2
= 2a
2
- 2d
2
a
2
- 10 d
2
= 0
So, 25=10 d
2
5
d
10
?
?
CBSE XI | Mathematics
Sample Paper – 2 Solution
So A.P. is 5 - v10, 5 -
5
10
, 5 +
5
10
, 5 + v10
Or 5 + v10, 5 +
5
10
, 5 -
5
10
, 5 - v10
8. Sn = (pn + qn
2
)
S1 = (p.1 + q.1
2
)
= p + q = a1
S2 = (p.2 + q.2
2
)
= 2p + 4q = a1 + a2
a2 = S2 - S1 = p + 3q
d = a2 - a1 = (p + 3 q) - (p + q) = 2q
9. If we need to prove something false, one counter example is sufficient.
(i) (a, a) ?R, for all a ?N is not true
For example take 2 ?N. we have 2 ? 2
2
, therefore (2, 2) ?R.
(ii) (a, b) ?R, implies (b, a) ?R is also not true for example take a = 9, b = 3.
As 9 = 3
2
, we have (9, 3) ?R, but 3 ? 9
2
, therefore (3, 9) ?R.
10. Let y = |2x – 1|
Differentiating w.r.t. x we get
? ?
? ?
2
2
2
2
2
dy 2x 1 d d x
2x 1 ............... x
dx dx dx x 2x 1
4x 2x 1
1
....... x
2x 1 2
??
? ??
? ? ? ?
??
?
??
??
?
? ? ?
?
OR
y = x sin x log x
dy dlog x dx dsinx
xsinx sinxlog x xlog x
dx dx dx dx
dy xsinx
sinxlog x xlog xcosx
dx x
dy
sinx sinxlog x xlog xcosx
dx
? ? ?
? ? ?
? ? ?
11. Equation of the circle is x
2
+y
2
– 3x + 5y – 4 = 0
? Centre is (3/2, -5/2)
Which is the midpoint of diameter having end points (2, 1) & (x, y)……… say
So by mid point formula
2 3 1 5
&
2 2 2 2
xy ? ? ?
??
? x = 1, y = -6
Page 4
CBSE XI | Mathematics
Sample Paper – 2 Solution
CBSE Board
Class XI Mathematics
Sample Paper – 2 Solution
SECTION – A
1. The sum of the infinite series will be:
2 3 4
1 1 1 1
...
3
3 3 3
? ? ? ?
=
1
1
3
1
2
1
3
?
?
OR
23
0.5 0.5555...
0.5 0.05 0.005 ...
5 5 5
...
10
10 10
5
10
1
1
10
5
9
?
? ? ? ? ?
? ? ? ? ?
?
?
?
2. Since A and B are disjoint sets, so their intersection is an empty or a null set. So the
statement is true.
3. cos cos sin sin
4 4 4 4
? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
cos
44
cos ( )
2
sin( )
?? ?? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ??
? ? ? ? ??
???
? ? ? ? ?
??
??
? ? ? ?
CBSE XI | Mathematics
Sample Paper – 2 Solution
4.
? ? ? ?
22
1 1 1 i 1 i 1 i 1 1
i
1 i 1 i 1 i 1 1 2 2
1i
???
? ? ? ? ? ?
? ? ? ?
?
1 1 1
11
Comparing with x iy, x ,y
22
1
y
2
Argument = tan tan tan 1
1
x4
2
? ? ?
? ? ?
??
??
?
? ? ? ? ?
??
??
??
SECTION – B
5.
22
4x + y = 100
22
2 2 2 2
xy
1
25 100
b 100,a 25;c b a 100 25 75 5 3
c 5 3 3
eccentricity,e
b 10 2
? ? ?
? ? ? ? ? ? ? ? ?
? ? ?
6. Probability of both the friends not having the same birthday is
365 364
365 365
?
So the probability of two friends having the same birthday is
365 364 364 1
= 1 1 1
365 365 365 365
? ? ? ? ? ?
OR
Let A be the event that the patient will have his teeth cleaned and B be the event that he
will have cavity filled.
P(A) = 0.44, P(B) = 0.24, P(A ? B) = 0.60
P(A n B) = P(A) + P(B) – P(A ? B)
= 0.44 + 0.24 – 0.60
= 0.08
7. Let the four parts be a - 2d, a - d, a + d, a + 2d
So a - 2d + a - d + a + d + a + 2d = 20
a = 5
22
22
[(a 2d)(a 2d)] 2
[(a d)(a d)] 3
(a 4d ) 2
3
(a d )
??
?
??
?
?
?
3a
2
- 12d
2
= 2a
2
- 2d
2
a
2
- 10 d
2
= 0
So, 25=10 d
2
5
d
10
?
?
CBSE XI | Mathematics
Sample Paper – 2 Solution
So A.P. is 5 - v10, 5 -
5
10
, 5 +
5
10
, 5 + v10
Or 5 + v10, 5 +
5
10
, 5 -
5
10
, 5 - v10
8. Sn = (pn + qn
2
)
S1 = (p.1 + q.1
2
)
= p + q = a1
S2 = (p.2 + q.2
2
)
= 2p + 4q = a1 + a2
a2 = S2 - S1 = p + 3q
d = a2 - a1 = (p + 3 q) - (p + q) = 2q
9. If we need to prove something false, one counter example is sufficient.
(i) (a, a) ?R, for all a ?N is not true
For example take 2 ?N. we have 2 ? 2
2
, therefore (2, 2) ?R.
(ii) (a, b) ?R, implies (b, a) ?R is also not true for example take a = 9, b = 3.
As 9 = 3
2
, we have (9, 3) ?R, but 3 ? 9
2
, therefore (3, 9) ?R.
10. Let y = |2x – 1|
Differentiating w.r.t. x we get
? ?
? ?
2
2
2
2
2
dy 2x 1 d d x
2x 1 ............... x
dx dx dx x 2x 1
4x 2x 1
1
....... x
2x 1 2
??
? ??
? ? ? ?
??
?
??
??
?
? ? ?
?
OR
y = x sin x log x
dy dlog x dx dsinx
xsinx sinxlog x xlog x
dx dx dx dx
dy xsinx
sinxlog x xlog xcosx
dx x
dy
sinx sinxlog x xlog xcosx
dx
? ? ?
? ? ?
? ? ?
11. Equation of the circle is x
2
+y
2
– 3x + 5y – 4 = 0
? Centre is (3/2, -5/2)
Which is the midpoint of diameter having end points (2, 1) & (x, y)……… say
So by mid point formula
2 3 1 5
&
2 2 2 2
xy ? ? ?
??
? x = 1, y = -6
CBSE XI | Mathematics
Sample Paper – 2 Solution
12. Since the centre of ellipse is at the origin & foci lie on y-axis, its equation is
? ?
22
22
2 2 2
2
22
22
22
2
2
xy
1............. (1)
ba
where b a 1 e
3
b a 1
4
7
ba
16
Sub in (1)
xy
1..............(2)
7
a
a
16
??
??
??
??
????
??
??
??
??
?
??
Also it passes through (6, 4)
? 576 + 112 = 7a
2
Substituting a
2
and b
2
in (1)
We get equation 16x
2
+ 7y
2
= 688.
OR
Comparing
22
xy
1
36 20
?? with
22
22
xy
1
ab
??
a
2
= 36 and b
2
= 20
b
2
= a
2
(1 – e
2
)
20 = 36(1 – e
2
)
36e
2
= 16
e
= 2/3
Distance between directrices =
2a 2 6
18
2
e
3
?
??
SECTION – C
13. Let A, B and C represent the set of students who received medals for Soccer, Basketball
and Cricket.
n(A) = 38, n(B) = 15, n(C) = 20, n(A ? B ? C) = 58, n(A ? B ? C) = 3
Using counting theorems,
n (A ? B ? C) = n(A) + n(B) + n(C) – n(A ? B) – n(B ? C) –n(A ? C) + n(A ? B ? C)
Substituting the values we get,
? 58 = 38 + 15 + 20 - n(A ? B) - n(B ? C) –n(A ? C) + 3
? n(A ? B) + n(B ? C) + n(A ? C) = 76 – 58 = 18
Now, each of n(A ? B), n(B ? C), n(A ? C) include the 3 students who received medals
for all three sports. Number of students who received medals in exactly two sports,
n(A ? B) – 3 + n(B ? C) –3 + n(A ? C) – 3= 18 – 3 – 3 – 3 = 9
Page 5
CBSE XI | Mathematics
Sample Paper – 2 Solution
CBSE Board
Class XI Mathematics
Sample Paper – 2 Solution
SECTION – A
1. The sum of the infinite series will be:
2 3 4
1 1 1 1
...
3
3 3 3
? ? ? ?
=
1
1
3
1
2
1
3
?
?
OR
23
0.5 0.5555...
0.5 0.05 0.005 ...
5 5 5
...
10
10 10
5
10
1
1
10
5
9
?
? ? ? ? ?
? ? ? ? ?
?
?
?
2. Since A and B are disjoint sets, so their intersection is an empty or a null set. So the
statement is true.
3. cos cos sin sin
4 4 4 4
? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ?
cos
44
cos ( )
2
sin( )
?? ?? ? ? ? ?
? ? ? ? ? ?
? ? ? ? ??
? ? ? ? ??
???
? ? ? ? ?
??
??
? ? ? ?
CBSE XI | Mathematics
Sample Paper – 2 Solution
4.
? ? ? ?
22
1 1 1 i 1 i 1 i 1 1
i
1 i 1 i 1 i 1 1 2 2
1i
???
? ? ? ? ? ?
? ? ? ?
?
1 1 1
11
Comparing with x iy, x ,y
22
1
y
2
Argument = tan tan tan 1
1
x4
2
? ? ?
? ? ?
??
??
?
? ? ? ? ?
??
??
??
SECTION – B
5.
22
4x + y = 100
22
2 2 2 2
xy
1
25 100
b 100,a 25;c b a 100 25 75 5 3
c 5 3 3
eccentricity,e
b 10 2
? ? ?
? ? ? ? ? ? ? ? ?
? ? ?
6. Probability of both the friends not having the same birthday is
365 364
365 365
?
So the probability of two friends having the same birthday is
365 364 364 1
= 1 1 1
365 365 365 365
? ? ? ? ? ?
OR
Let A be the event that the patient will have his teeth cleaned and B be the event that he
will have cavity filled.
P(A) = 0.44, P(B) = 0.24, P(A ? B) = 0.60
P(A n B) = P(A) + P(B) – P(A ? B)
= 0.44 + 0.24 – 0.60
= 0.08
7. Let the four parts be a - 2d, a - d, a + d, a + 2d
So a - 2d + a - d + a + d + a + 2d = 20
a = 5
22
22
[(a 2d)(a 2d)] 2
[(a d)(a d)] 3
(a 4d ) 2
3
(a d )
??
?
??
?
?
?
3a
2
- 12d
2
= 2a
2
- 2d
2
a
2
- 10 d
2
= 0
So, 25=10 d
2
5
d
10
?
?
CBSE XI | Mathematics
Sample Paper – 2 Solution
So A.P. is 5 - v10, 5 -
5
10
, 5 +
5
10
, 5 + v10
Or 5 + v10, 5 +
5
10
, 5 -
5
10
, 5 - v10
8. Sn = (pn + qn
2
)
S1 = (p.1 + q.1
2
)
= p + q = a1
S2 = (p.2 + q.2
2
)
= 2p + 4q = a1 + a2
a2 = S2 - S1 = p + 3q
d = a2 - a1 = (p + 3 q) - (p + q) = 2q
9. If we need to prove something false, one counter example is sufficient.
(i) (a, a) ?R, for all a ?N is not true
For example take 2 ?N. we have 2 ? 2
2
, therefore (2, 2) ?R.
(ii) (a, b) ?R, implies (b, a) ?R is also not true for example take a = 9, b = 3.
As 9 = 3
2
, we have (9, 3) ?R, but 3 ? 9
2
, therefore (3, 9) ?R.
10. Let y = |2x – 1|
Differentiating w.r.t. x we get
? ?
? ?
2
2
2
2
2
dy 2x 1 d d x
2x 1 ............... x
dx dx dx x 2x 1
4x 2x 1
1
....... x
2x 1 2
??
? ??
? ? ? ?
??
?
??
??
?
? ? ?
?
OR
y = x sin x log x
dy dlog x dx dsinx
xsinx sinxlog x xlog x
dx dx dx dx
dy xsinx
sinxlog x xlog xcosx
dx x
dy
sinx sinxlog x xlog xcosx
dx
? ? ?
? ? ?
? ? ?
11. Equation of the circle is x
2
+y
2
– 3x + 5y – 4 = 0
? Centre is (3/2, -5/2)
Which is the midpoint of diameter having end points (2, 1) & (x, y)……… say
So by mid point formula
2 3 1 5
&
2 2 2 2
xy ? ? ?
??
? x = 1, y = -6
CBSE XI | Mathematics
Sample Paper – 2 Solution
12. Since the centre of ellipse is at the origin & foci lie on y-axis, its equation is
? ?
22
22
2 2 2
2
22
22
22
2
2
xy
1............. (1)
ba
where b a 1 e
3
b a 1
4
7
ba
16
Sub in (1)
xy
1..............(2)
7
a
a
16
??
??
??
??
????
??
??
??
??
?
??
Also it passes through (6, 4)
? 576 + 112 = 7a
2
Substituting a
2
and b
2
in (1)
We get equation 16x
2
+ 7y
2
= 688.
OR
Comparing
22
xy
1
36 20
?? with
22
22
xy
1
ab
??
a
2
= 36 and b
2
= 20
b
2
= a
2
(1 – e
2
)
20 = 36(1 – e
2
)
36e
2
= 16
e
= 2/3
Distance between directrices =
2a 2 6
18
2
e
3
?
??
SECTION – C
13. Let A, B and C represent the set of students who received medals for Soccer, Basketball
and Cricket.
n(A) = 38, n(B) = 15, n(C) = 20, n(A ? B ? C) = 58, n(A ? B ? C) = 3
Using counting theorems,
n (A ? B ? C) = n(A) + n(B) + n(C) – n(A ? B) – n(B ? C) –n(A ? C) + n(A ? B ? C)
Substituting the values we get,
? 58 = 38 + 15 + 20 - n(A ? B) - n(B ? C) –n(A ? C) + 3
? n(A ? B) + n(B ? C) + n(A ? C) = 76 – 58 = 18
Now, each of n(A ? B), n(B ? C), n(A ? C) include the 3 students who received medals
for all three sports. Number of students who received medals in exactly two sports,
n(A ? B) – 3 + n(B ? C) –3 + n(A ? C) – 3= 18 – 3 – 3 – 3 = 9
CBSE XI | Mathematics
Sample Paper – 2 Solution
14. cos6 cos3 (2 ) ? ? ?
? ?
? ?
??
? ? ? ? ? ? ? ? ?
??
? ? ? ?
? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ?
??
??
? ? ? ? ? ? ? ? ? ? ? ? ? ?
????
??
? ? ? ? ? ? ? ?
33
3
3
2 2 2
2
6 4 2 2
6 4 2
4cos (2 ) 3cos(2 ) Using,cos3 4cos 3cos
4 cos(2 ) 3cos(2 )
4 2cos 1 3 2cos 1 Using cos2 =2cos 1
4 8cos 3 4cos 1 3 2cos 1 1 3 2cos 1
32cos 48cos 24cos 4
? ?
??
? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ?
2
6 4 2
6 4 2
6 4 2
6cos 3
32cos 48cos 18cos 1
2cos6 2 32cos 48cos 18cos 1
64cos 96cos 36cos 2
OR
Using sin3? = 3 sin? – 4 sin³? and cos3? = 4 cos³? – 3 cos? in L.H.S.
33
sin3 cos3
L.H.S
sin cos
3sin 4sin 4cos 3cos
sin cos
sin (3 4sin² ) cos (4cos² 3)
sin cos
= 3 - 4 sin² - 4 cos² + 3
= 6 - 4 sin² - 4 cos²
= 6 - 4(sin² + cos² )
= 6 - 4
= 2
= R.H.S.
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15. Five children could be arranged in 5! ways.
(i) If x and y have to sit together, then taking x and y as 1 unit there are 4 ways of
arranging them and the two can interchange places, so 2! x 4! = 48 ways
(ii) Number of ways in which the two boys x and y never sit together,
Total ways - ways in which x and y are together = 5! - 2! x 4! = 72 ways
OR
There are 9 places in all i.e. 1, 2, 3, 4, 5, 6, 7, 8, and 9.
Out of these, 5 are odd and 4 are even.
The 5 odd places i.e. 1, 3, 5, 7, and 9 have to be occupied by the 5 men as the women do
not have to sit on these.
This they can do in
5
P5 ways = 5!
Now the 4 even places i.e., 2, 4, 6, 8 have to be occupied by the 4 women
This they can do in
4
P4 ways = 4!
Together the men and women can be seated in 5! x 4! = 120 x 24 = 2880 ways
16. Let P(x, y, z) be the required point.
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