Nine members of a family are standing in a row. Their average age is 70. The average age of the first four members in the row is 64 and the average age of the last seven members in the row is 80. What is the average age of the third and fourth member in the row?

- a)78
- b)86
- c)93
- d)89
- e)87

Correct answer is option 'C'. Can you explain this answer?

Related Test: NMAT Quantitative Skills MCQ Quiz - 3

78 Answers

Venky Dhawan
answered
Apr 21, 2020

The avg. age of 9 members is 70

so s1+ s2 + to s9/ 9= 70 = 70Ã—9 = 630

as the avg. age of last 7 member is 80

80Ã— 7 = 560 now..

630 - 560= 70

which is the combined age of s1 and s2.

as it is giver avg of first 4 members is 64 so the combined age is 256

from which 256 - 70= 186

which is combined age of s3 and s4 so the avg is 186/ 2 = 93.

so s1+ s2 + to s9/ 9= 70 = 70Ã—9 = 630

as the avg. age of last 7 member is 80

80Ã— 7 = 560 now..

630 - 560= 70

which is the combined age of s1 and s2.

as it is giver avg of first 4 members is 64 so the combined age is 256

from which 256 - 70= 186

which is combined age of s3 and s4 so the avg is 186/ 2 = 93.

Manya Mehta
answered
Jun 25, 2020

Simply Apply Formula of Average. BUT LOOK THE QUESTION FROM THE ANGLE OF VENN DIAGRAM IN TERMS OF SETS.

Average = Total sum of nos./ Total nos.

Here Avg. of 9 members in a row is given 70.

So Total age is 70* 9 members = 630. ( AUB )

same as above

Average of first 4 is 64.

so Total age is 64*4 members = 256. ( A )

Average of last 7 is 80.

so Total age is 80*7 members = 560. ( B )

SO ON CALCULATION WE GET

( A^B) A INTERSECTION B = (A) + (B) - (AUB)

= 256+560-630 = 186 ( TOTAL AGE OF 3RD N 4TH MEMBER IN A ROW)

THEREFORE AVERAGE AGE OF 3RD N 4TH MEMBER IN A ROW IS

186/ 2= 93

SO THE ANSWER IS OPTION C that is 93.

Average = Total sum of nos./ Total nos.

Here Avg. of 9 members in a row is given 70.

So Total age is 70* 9 members = 630. ( AUB )

same as above

Average of first 4 is 64.

so Total age is 64*4 members = 256. ( A )

Average of last 7 is 80.

so Total age is 80*7 members = 560. ( B )

SO ON CALCULATION WE GET

( A^B) A INTERSECTION B = (A) + (B) - (AUB)

= 256+560-630 = 186 ( TOTAL AGE OF 3RD N 4TH MEMBER IN A ROW)

THEREFORE AVERAGE AGE OF 3RD N 4TH MEMBER IN A ROW IS

186/ 2= 93

SO THE ANSWER IS OPTION C that is 93.

Pusp Kumar Vyas
answered
May 12, 2020

N1+n2+ ....+n9=630 --->1

n1+ ....+n4=256 --->2

n3+....+n9=560 --->3

Adding eqn 2 and 3

n3+n4+(n1+....+n9)=256+560

n3+n4+630=816

n3+n4=186

(n3+n4)/2=93

Suman Devi
answered
Apr 03, 2020

S9/9=70

S9=630

S4/4=64

S4=256

S7/7=80

S7=560

S4+S7=256+560

=816

then,S2=816-630

=186

average of third and fourth member = 186/2=93

S9=630

S4/4=64

S4=256

S7/7=80

S7=560

S4+S7=256+560

=816

then,S2=816-630

=186

average of third and fourth member = 186/2=93

Luvy Goel
answered
Jul 23, 2020

Average of first 9 number 70 so 70 Ã—9=630

average of first 4 number 64 so 64Ã—4=256

average of last 7 number 80 so 80Ã—7=560

now 560+256=630 as third and fourth number come in both first 4 and last 7

therefore 816-630 =186

as the sum of 4and5 number is 186 so the average is 186/2=93

average of first 4 number 64 so 64Ã—4=256

average of last 7 number 80 so 80Ã—7=560

now 560+256=630 as third and fourth number come in both first 4 and last 7

therefore 816-630 =186

as the sum of 4and5 number is 186 so the average is 186/2=93

Kulwinder Kaur
answered
Feb 20, 2020

Let the age of the members in the row be A, B, C, D, E, F, G, H and I.

∴ A + B + C + D + E + F + G + H + I = 1 0 * 9 = 630 ...(i)

Since the average age of the first four members is 64 years,

A + B + C + D = 6 4 x 4 = 256 ...(ii)

§jnce the average age of the last seven members is 80 years,

C + D + E + F + G + H + I = 80 x 7 = 560 ...(iii)

Subtracting (iii) from (i),

A + B = 70 ... (iv)

Subtracting (iv) from (ii),

C + D= 186

Subtracting (iv) from (ii),

C + D= 186

∴ Averageage of third and four the member =

Hence, option 3.

Priya Tiwari
answered
Jun 23, 2020

70*9-80*7=70,total age of first two person.

average of 3rd or 4th = total of first 4person - total of first two person/2

= 64*4-70/2=256-70/2=186/2=93.

average of 3rd or 4th = total of first 4person - total of first two person/2

= 64*4-70/2=256-70/2=186/2=93.

Muskan Seth
answered
Jul 22, 2020

Average age of 9 people = 70

Therefore, total average age of 9 people = 70Ã—9=630

average age of first four members = 64

therefore , average age of four members = 64Ã—4= 256

average age of the last seven members = 80

therfore , average age of last seven members= 80Ã—7 =560

AVERAGE AGE OF 9 PEOPLE- AVERAGE AGE OF LAST 7 MEMBERS = average age of first two members

therefore , 630-560=70

then .... average age of four members-average age of first two members = 256- 70 = 186 ( average age of 3rd nd 4th member )

average age of 3rd member/ 4th member = 186/2 = 93 .

Therefore, total average age of 9 people = 70Ã—9=630

average age of first four members = 64

therefore , average age of four members = 64Ã—4= 256

average age of the last seven members = 80

therfore , average age of last seven members= 80Ã—7 =560

AVERAGE AGE OF 9 PEOPLE- AVERAGE AGE OF LAST 7 MEMBERS = average age of first two members

therefore , 630-560=70

then .... average age of four members-average age of first two members = 256- 70 = 186 ( average age of 3rd nd 4th member )

average age of 3rd member/ 4th member = 186/2 = 93 .

Sonal Vishwakarma
answered
Apr 30, 2020

4*64=256

7*80=560

9*70=630

Hence, 256+560-630=186

The average age of two person would be,

186/2= 93

7*80=560

9*70=630

Hence, 256+560-630=186

The average age of two person would be,

186/2= 93

Vishal Agarwal
answered
Mar 23, 2020

If average age of nine members of a family standing in a row = 70

Total age of nine members of the family standing in a row= 70*9=630

If average age of first four members of the family standing in a row=64

Total age of first four members of the family standing in a row=64*4=256

If average age of last seven members standing in a row = 80

Total age of last seven members standing in a row= 80*7=560

Therefore, Total age of first two members of the family standing in a row= 630-560= 70

Now, Total age of 3rd and 4th members of the family standing in a row= 256-70=186

Average age of 3rd and 4th members of the family standing in a row= 186Ã·2= 93

Total age of nine members of the family standing in a row= 70*9=630

If average age of first four members of the family standing in a row=64

Total age of first four members of the family standing in a row=64*4=256

If average age of last seven members standing in a row = 80

Total age of last seven members standing in a row= 80*7=560

Therefore, Total age of first two members of the family standing in a row= 630-560= 70

Now, Total age of 3rd and 4th members of the family standing in a row= 256-70=186

Average age of 3rd and 4th members of the family standing in a row= 186Ã·2= 93

Gautami Parate
answered
Aug 22, 2020

Let the ages of 9 members be a,b,c,d,e,f,g,h,i resp.

According to condition,

(a+b+c+d+e+f+g+h+i)/9 = 70 ____(1)

(a+b+c+d)/4 = 64

=> a+b = 64(4)-c-d _____(2)

Also,

(c+d+e+f+g+h+i)/7 = 80

=> e+f+g+h+i = 80(7)-c-d _____(3)

put (2) and (3) in eqn (1), we get

(256-c-d+c+d+560-c-d)/9 = 70

=> 816-c-d = 70(9)

=> c+d = 816-630

=> c+d = 186

Taking Average of c and d , we get

c+d/2 = 186/2 = 93

Answer: Option C

According to condition,

(a+b+c+d+e+f+g+h+i)/9 = 70 ____(1)

(a+b+c+d)/4 = 64

=> a+b = 64(4)-c-d _____(2)

Also,

(c+d+e+f+g+h+i)/7 = 80

=> e+f+g+h+i = 80(7)-c-d _____(3)

put (2) and (3) in eqn (1), we get

(256-c-d+c+d+560-c-d)/9 = 70

=> 816-c-d = 70(9)

=> c+d = 816-630

=> c+d = 186

Taking Average of c and d , we get

c+d/2 = 186/2 = 93

Answer: Option C

Raj Kamal
answered
Apr 19, 2020

Average age of 3rd and 4 th member.=(sum of 3rs and 4th members' age in row) /2

to get sum of sum of 3rd and 4 th mem. age=. (sum of 4 memb. from start + sum of 7 mem. from last)- sum of 9 mem

=(256+560)-630

=816-630

186

divide by 2 we get avg.- 93

to get sum of sum of 3rd and 4 th mem. age=. (sum of 4 memb. from start + sum of 7 mem. from last)- sum of 9 mem

=(256+560)-630

=816-630

186

divide by 2 we get avg.- 93

Akshay
answered
May 01, 2020

What kind of family it is ? How the average age of a family can be 80 ?

Krishna Kant Murari Raja
answered
May 17, 2020

9 members = Average- 70= 630

First 4 - Average- 64 = 256

Last 7- Average- 80 = 560

Therefore total = 256+560= 816

Average od 3rd & 4th = 816 - 630= 186

186/2= 93 Answer

First 4 - Average- 64 = 256

Last 7- Average- 80 = 560

Therefore total = 256+560= 816

Average od 3rd & 4th = 816 - 630= 186

186/2= 93 Answer

Monu Sharma
answered
Jul 06, 2020

70*9=630

and 80*7 = 560

630-560= 70. 1st and 2nd sum

so 64*4= 256

3rd + 4th sum = 256-70= 186

avg= 186/2= 93

and 80*7 = 560

630-560= 70. 1st and 2nd sum

so 64*4= 256

3rd + 4th sum = 256-70= 186

avg= 186/2= 93

Abhishek Kumar
answered
Apr 23, 2020

First sum of the ages of 9 people= 70Ã—9=630

second Sum of the ages of first 4 people =64Ã—4=256

Third sum of the ages of last 7 people =80Ã—7=560

subtract the sum of the ages of 7 people from ages of 9 people.= 630- 560=70. this is the value of first 2 people

And substitute this value in the sum of the ages of first four peopl

Let the people are t1, t2, t3, t9

t1+.....+t9=630

t3+...+t9=560

subtract this t1+t2= 70

and

t1+t2+t3+t4=256

70+t3+t4=256

t3+t4=186

then Avg. of t3 and t4 is 186/2 =93

the ansr is 93

second Sum of the ages of first 4 people =64Ã—4=256

Third sum of the ages of last 7 people =80Ã—7=560

subtract the sum of the ages of 7 people from ages of 9 people.= 630- 560=70. this is the value of first 2 people

And substitute this value in the sum of the ages of first four peopl

Let the people are t1, t2, t3, t9

t1+.....+t9=630

t3+...+t9=560

subtract this t1+t2= 70

and

t1+t2+t3+t4=256

70+t3+t4=256

t3+t4=186

then Avg. of t3 and t4 is 186/2 =93

the ansr is 93

Abhishek Kumar
answered
Apr 22, 2020

Total marks of first four=64*4=256

Total marks of last 7=80*7=560

By Adding both you will get 256+560=816

Now the total marks of all 9 students =70*9=630

So there are difference of 186 and we now that third and fourth counts double so third and fourth both are equal to 816-630=186 .

It is the total value of both 3rd and 4th. So obviously the average for third and fourth is 186/2=93.

so correct answer is 93.

Total marks of last 7=80*7=560

By Adding both you will get 256+560=816

Now the total marks of all 9 students =70*9=630

So there are difference of 186 and we now that third and fourth counts double so third and fourth both are equal to 816-630=186 .

It is the total value of both 3rd and 4th. So obviously the average for third and fourth is 186/2=93.

so correct answer is 93.

Swetha Viriyala
answered
Jul 11, 2020

Assume the persons as A1,A2,A3.....A9

Given average of A1 till A9 is 70. So sum of all is 70*9 = 630 (1)

Given average of first 4 i.e., A1 to A4 is 64. So sum of A1 to A4 is 64*4 = 256 (2)

Given average of last 7 i.e., A3 to A9 is 80. So sum of A3 to A9 is 80*7 = +560 (3)

Add (2)&(3)

We can see that A1 to A9 + A3 + A4 will be the sum = 256+560 = 816 (4)

(4)-(1) = A3 + A4 (since (1) = sum of A1 to A9) = 816 - 630 = 186

Now, average of A3 & A4 = 186/2 = 93 -> Ans

Given average of A1 till A9 is 70. So sum of all is 70*9 = 630 (1)

Given average of first 4 i.e., A1 to A4 is 64. So sum of A1 to A4 is 64*4 = 256 (2)

Given average of last 7 i.e., A3 to A9 is 80. So sum of A3 to A9 is 80*7 = +560 (3)

Add (2)&(3)

We can see that A1 to A9 + A3 + A4 will be the sum = 256+560 = 816 (4)

(4)-(1) = A3 + A4 (since (1) = sum of A1 to A9) = 816 - 630 = 186

Now, average of A3 & A4 = 186/2 = 93 -> Ans

Garima Pal
answered
May 13, 2020

Let the age of nine people be a,b,c,d,e,f,g,h and i

Subtract the sum of last 7 no.s (80*7) from the sum of 9 no.s (70*9) then you will get the sum of a+b =70 .

Now subtract the sum of a+b from the sum of a+b+c+d(64*4) .

you will get c+d =186

now the average of third and fourth that is c+d will be 186/2=93 ( option c)

Subtract the sum of last 7 no.s (80*7) from the sum of 9 no.s (70*9) then you will get the sum of a+b =70 .

Now subtract the sum of a+b from the sum of a+b+c+d(64*4) .

you will get c+d =186

now the average of third and fourth that is c+d will be 186/2=93 ( option c)

Khushi Popat
answered
Aug 06, 2020

Total age of members=average Ã— no. of members

i.e

70Ã—9 =630.

given that: the average age of 1st four member is 64

64Ã—4 =256. (total age of member 1 to 4)

therefore the age of last 5 members will be

630-256= 374. (total age of member 5 to 9)

given that: the average age of the last seven members i.e member 3 to 9 is 80

80Ã—7=560. (total age of member 3 to 9)

to get the total age of 3rd and 4th member

560-374=186

average = 186/2 =93. option c

i.e

70Ã—9 =630.

given that: the average age of 1st four member is 64

64Ã—4 =256. (total age of member 1 to 4)

therefore the age of last 5 members will be

630-256= 374. (total age of member 5 to 9)

given that: the average age of the last seven members i.e member 3 to 9 is 80

80Ã—7=560. (total age of member 3 to 9)

to get the total age of 3rd and 4th member

560-374=186

average = 186/2 =93. option c

Rishabh Upadhyay
answered
Sep 28, 2020

Sum of age of 9 members=630

sum of age of first 4 members= 256 @1

sum of age of last seven members =560 @2

adding @1 &@2 we get additional 3 and 4

560+256-630 gives you 186 sum of age of 3&4 member

average of 3&4 member will be

186Ã·2 =93

sum of age of first 4 members= 256 @1

sum of age of last seven members =560 @2

adding @1 &@2 we get additional 3 and 4

560+256-630 gives you 186 sum of age of 3&4 member

average of 3&4 member will be

186Ã·2 =93

Tarun Sharma
answered
Jul 13, 2020

Average age of 9 members is 70 then total of there age would be 630.

average age of first four members is 64 then total of there age would be 256

average age of last seven members is 80 so total of there age would be 560

total of age of first two members = total age of 9 member - total age of last seven members = 630-540=70

than total age of 3rd +4th member of row = 256-70=186

than average age would be 186/2= 93 answer c is correct.

average age of first four members is 64 then total of there age would be 256

average age of last seven members is 80 so total of there age would be 560

total of age of first two members = total age of 9 member - total age of last seven members = 630-540=70

than total age of 3rd +4th member of row = 256-70=186

than average age would be 186/2= 93 answer c is correct.

Divyansh Chandak
answered
Apr 19, 2020

Total age=630

total age of first 4 - 256

total age of last 7 - 560

required average -- 560+256-630/2----93

total age of first 4 - 256

total age of last 7 - 560

required average -- 560+256-630/2----93

Ankit Verma
answered
Aug 13, 2020

Sum of 9 = 70*9=630

sum of first 4 = 64*4 = 256

sum of last 7 = 80*7 = 560

sum of first 4 and last 7 = 256+ 560 = 816

sum of 3rd and 4th number= 816 - 630 = 186

average of 3rd and 4th number = 186/2 = 93

sum of first 4 = 64*4 = 256

sum of last 7 = 80*7 = 560

sum of first 4 and last 7 = 256+ 560 = 816

sum of 3rd and 4th number= 816 - 630 = 186

average of 3rd and 4th number = 186/2 = 93

Anshul Sancheti
answered
4 weeks ago

Let 9 members be A,B,C,D,E,F,G,H,I

A+B+C+D+E+F+G+H+I = 9*70 => 630 (given) (i)

A+B+C+D = 4*64 => 256 (given). (ii)

C+D+E+F+G+H+I = 7*80 => 560 (given). (iii)

On adding (ii) and (iii)

A+B+C+D+C+D+E+F+G+H+I = 816

Now Subtract it from (i)

(A+B+C+D+C+D+E+F+G+H+I) - (A+B+C+D+E+F+G+H+I)= 816-630

C+D = 186

Average would be 186/2 = 93 Years

A+B+C+D+E+F+G+H+I = 9*70 => 630 (given) (i)

A+B+C+D = 4*64 => 256 (given). (ii)

C+D+E+F+G+H+I = 7*80 => 560 (given). (iii)

On adding (ii) and (iii)

A+B+C+D+C+D+E+F+G+H+I = 816

Now Subtract it from (i)

(A+B+C+D+C+D+E+F+G+H+I) - (A+B+C+D+E+F+G+H+I)= 816-630

C+D = 186

Average would be 186/2 = 93 Years

Anumol Thankappan
answered
6 days ago

9 members x 70yrs(avg) = 630 --- (1)

4 members x 64 yrs(avg) = 256 --- (2)

7 members x 80 yrs(avg) = 560 --- (3)

.

(2) + (3) = 11 members with sum of age as 816 --- (4)

(4) - (1) = 2 members ie; sum of ages of 3rd and 4th person= 186. Hence, average= 186/2= 93 years. Answer is 93.

4 members x 64 yrs(avg) = 256 --- (2)

7 members x 80 yrs(avg) = 560 --- (3)

.

(2) + (3) = 11 members with sum of age as 816 --- (4)

(4) - (1) = 2 members ie; sum of ages of 3rd and 4th person= 186. Hence, average= 186/2= 93 years. Answer is 93.

Veera Reddy Konabhai
answered
Feb 10, 2020

Consider first two members as set A, third person as B, fourth person as C and remaining five membes as set D.

given (A+B+C+D)/9 = 70 => A+B+C+D = 630

and (A+B+C)/4 = 64 => A+B+C = 256 ----> smt1

and (B+C+D)/7 = 80 => B+C+D = 560 ----->smt2

now add smt1 and smt2 that gives us A+B+C+B+C+D = 816 and given A+B+C+D is 630 subitting in previous equation we get B+C+630 = 816 and solving gives us B+C = 186. now we want avg of B,C that is (B+C)/2 = 186/2 = 93

given (A+B+C+D)/9 = 70 => A+B+C+D = 630

and (A+B+C)/4 = 64 => A+B+C = 256 ----> smt1

and (B+C+D)/7 = 80 => B+C+D = 560 ----->smt2

now add smt1 and smt2 that gives us A+B+C+B+C+D = 816 and given A+B+C+D is 630 subitting in previous equation we get B+C+630 = 816 and solving gives us B+C = 186. now we want avg of B,C that is (B+C)/2 = 186/2 = 93

Shyam Sundar Prasad
answered
Oct 03, 2020

9Ã—70 = 630

64Ã—4= 256

80Ã—7 = 560

Therefore sum of third and fourth age = (256+560) - 630

= 186/ 2 = 93

64Ã—4= 256

80Ã—7 = 560

Therefore sum of third and fourth age = (256+560) - 630

= 186/ 2 = 93

Rishita Roy
answered
Apr 27, 2020

Let the 9 members be A, B, C, D, E, F, G, H, I. Now the number of member's ages divided by 9 is equal to 70. So the sum of the ages will be 70*9=630. Now, average age of first 4 members is equal to 64. Therefore the sum of the age of the first 4 members is 64*4=256. Again, average age of the last 7 members is 80. So the sum of the age of the members is 80*7=560. Now put the age value of the first 4 members in the sum of all the 9 members , ie, A+B+C+D+E+F+G+H+I=630.

or, 256+E+F+G+H+I=630

or, E+F+G+H+I=630-256=374.

Now, Put the above found age value in the sum of the last 7 members, ie,

C+D+E+F+G+H+I=560

or, C+D+374=560

or, C+D=560-374=186

Average of C+D=186/2=93.

So the average age of the third and fourth member is 93.

or, 256+E+F+G+H+I=630

or, E+F+G+H+I=630-256=374.

Now, Put the above found age value in the sum of the last 7 members, ie,

C+D+E+F+G+H+I=560

or, C+D+374=560

or, C+D=560-374=186

Average of C+D=186/2=93.

So the average age of the third and fourth member is 93.

Miss Rai
answered
Jul 21, 2020

We can use the de Morgan's law in this.

as we know

n(AUB)=n(A)+n(B)-n(A^B)

so we have

A=set of first 4 members

B=set of last seven members

AUB=Set of all 9 members

note that when we say set we are talking about the sum

I.e. n(A)=64Ã—4

n(B)=80Ã—7

n(AUB)=70Ã—9

n(A^B)=186

3rd+4th)=186Ã·2

=93

as we know

n(AUB)=n(A)+n(B)-n(A^B)

so we have

A=set of first 4 members

B=set of last seven members

AUB=Set of all 9 members

note that when we say set we are talking about the sum

I.e. n(A)=64Ã—4

n(B)=80Ã—7

n(AUB)=70Ã—9

n(A^B)=186

3rd+4th)=186Ã·2

=93

Navneet Mishra
answered
Jun 29, 2020

Let the members are :-

a1, a2, a3, a4, a5, a6, a7, a8, a9

Avg9 :- (a1+a2+a3+a4+a5+a6+a7+a8+a9)/9 =70

a1+a2+a3+a4+a5+a6+a7+a8+a9 = 630 (1)

Avg4:- (a1+a2+a3+a4)/4 = 64

a1+a2+a3+a4 = 256 (2)

From eq(1) - (2)

a5+a6+a7+a8+a9 =374 (3)

Avg_last7:- (a3+a4+a5+a6+a7+a8+a9)/7 = 80

a3+a4+a5+a6+a7+a8+a9 = 560 (4)

From eq(4) - eq(3)

a3+a4 = 186

(a3+a4)/2 =186/2

Avg of 3 and 4 members :- (a3+a4)/2 = 93

Option(c)

a1, a2, a3, a4, a5, a6, a7, a8, a9

Avg9 :- (a1+a2+a3+a4+a5+a6+a7+a8+a9)/9 =70

a1+a2+a3+a4+a5+a6+a7+a8+a9 = 630 (1)

Avg4:- (a1+a2+a3+a4)/4 = 64

a1+a2+a3+a4 = 256 (2)

From eq(1) - (2)

a5+a6+a7+a8+a9 =374 (3)

Avg_last7:- (a3+a4+a5+a6+a7+a8+a9)/7 = 80

a3+a4+a5+a6+a7+a8+a9 = 560 (4)

From eq(4) - eq(3)

a3+a4 = 186

(a3+a4)/2 =186/2

Avg of 3 and 4 members :- (a3+a4)/2 = 93

Option(c)

Fathima Sahla
answered
2 days ago

The average age of 9 members is 70

So s1+s2+to s9=70=70Ã—9=630

as the average age of last 7 member is 80

80Ã—7=560 now

630-560=70

which is the combined age of s1and s2 as it is given average of first 4 members

is 64 So the combined age is 256

from which 256-70=186

which is combined age of s3 and s4 So the average is 186Ã·2=93.

So s1+s2+to s9=70=70Ã—9=630

as the average age of last 7 member is 80

80Ã—7=560 now

630-560=70

which is the combined age of s1and s2 as it is given average of first 4 members

is 64 So the combined age is 256

from which 256-70=186

which is combined age of s3 and s4 So the average is 186Ã·2=93.

This discussion on Nine members of a family are standing in a row. Their average age is 70. The average age of the first four members in the row is 64 and the average age of the last seven members in the row is 80. What is the average age of the third and fourth member in the row?a)78b)86c)93d)89e)87Correct answer is option 'C'. Can you explain this answer? is done on EduRev Study Group by CAT Students. The Questions and
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