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March 15, 2018 11:11 AM

Hello sir,

This question was asked in Cat 2017 slot- 1, please explain the solution in details.

Arun's present age in years is 40% of Barun's. In another few years, Arun's age will be half of Barun's. By what percentage will Barun's age increase during this period?

1 Answer

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March 16, 2018 11:04 AM

A =0.4B

A + x =(B +x)/2

2A + 2x = B + x

x = B - 2A

x = B - 0.8B

x =0.2B

=> B =5x

After x year, the age of Barun's = 5x + x = 6x

Percentage increases = [(6x - 5x)/5x ] x 100 = 20%

Second method,

Let Barun's age is 100 years and Arun's age is 40 years.

After x years,

40 + x = (100 + x) /2

80 + 2x = 100 + x

x = 20

Percentage = 20%