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  • 1 Post By Denis
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June 19th, 2018, 01:14 AM   #1
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How to do the problem?

The present age of A is equal to B's age ten years ago. Four years hence, the ratio of the ages of A and B will be 3:5. Find the present age of A.

Solution: A = X

B = Y

X= Y - 10

Y = X + 10

Four years hence

X+ 4/ Y+ 4 = 3/5

Substitute Y in the equation:

X + 4 / X + 14 = 3/5

X = 22/2 = 11 years.

My doubt: They didn't mention B is older to A or vice versa. How to do the problem?
Ganesh Ujwal is offline  
 
June 19th, 2018, 01:41 AM   #2
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Four years hence, "the ratio of the ages of A and B will be 3:5" means that B's age will exceed A's age by 2/3 of A's age, but we know that B is 10 years older than A, so A's age then will be 15 years and B's age will be 25 years (because 10 is 2/3 of 15).

It follows that A's present age is 15 years - 4 years, which is 11 years.
skipjack is offline  
June 19th, 2018, 12:23 PM   #3
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A li'l diagram always help:
Code:
    A-10                A         A+4

    B-10                B         B+4

<....|................NOW........|.........>
A = B-10 [1]

(A+4)/(B+4) = 3/5 [2]
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