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The ratio of the present age of A and B is 3 : 1.

The ratio of the present age of A and B is 3 : 1. Five years ago, the ratio of their ages was 5 : 1. The age of A (in years) after eight years will be:
A और B की वर्तमान आयु का अनुपात 3 : 1 है। पांच वर्ष पहले, उनकी आयु का अनुपात 5 : 1 था। आठ वर्ष बाद A की आयु (वर्ष में) कितनी होगी?

40 22 38 30

Detailed Solution & Logic

Correct Answer:

Given ratio of present ages:
$A : B = 3 : 1$
So let
$A = 3x,; B = x$
Five years ago:
$\dfrac{3x - 5}{x - 5} = \dfrac{5}{1}$
Cross-multiply:
$3x - 5 = 5(x - 5)$
$3x - 5 = 5x - 25$
$20 = 2x$
$x = 10$
So,$A = 3x = 30$
Age of A after 8 years:
$30 + 8 = 38$