Latest CAT Aptitude Question SOLUTION: the ratio of the ages ofA and B seven years ago was 3:4.the ratio of their ages nine years from now will be 7:8.what is B's age present ar present?

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(#M40018413) CAT question Keep an EYE

the ratio of the ages ofA and B seven years ago was 3:4.the ratio of their ages nine years from now will be 7:8.what is B's age present ar present?

Asked In CAT MohanRaj (11 years ago)

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Ann Mary Jolly  (11 years ago)

Let x and y be the present ages of A and B respectively.
Then according to what is given,(x-7)/(y-7)=3/4 and (x+9)/(y+9)=7/8
On simplifying we get, 4x-3y = 7 ....(1) and 8x-7y = -9 ....(2)
Multiplying (1) by 2,we get 8x-6y = 14 ....(3)
Now subtracting 2 from 3 we get -6y+7y=23.
y=23 which is the present age of B

Is this solution Helpfull? Yes (3) | No   

Alka Shakya  (11 years ago)

Ans:A- 19, B- 23
Solution: (3x+16)/(4x+16)= 7/8
x= 4.
A= 3*4+7=19
B = 4*4+7 =23

Is this solution Helpfull? Yes (2) | No (1)  

Vinay Sipani   (11 years ago)

(A - 7) / (B - 7) = 3 / 4
=> 4A - 28 = 3B - 21
=> 4A - 3B = 7 -------(2)

(A - 9) / (B - 9) = 7/8
=> 8A - 72 = 7B - 63
=> 8A - 7B = 9 -------(1)

Solving 1 and 2,
present age of B = 5

Is this solution Helpfull? Yes | No (2)  

Jasmine Khan  (11 years ago)

let the current ages of a and b are x & y.
before 7 yrs their age ratio was 3:4
=>x-7/y-7=3/4 =>4x-3y=7
and after 9 yrs their age ratio will be 7:8
=> x+9/y+9=7/8 => 8x-7y=-9
now solve both the equation
we get,
x=19 and y=23

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