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P is twice as fast as Q and R together .Working together ,all three can do a work in 21 days.In how many days can Q and R together do the work


Simran 9th Jan, 2020
Answer (1)
KUNAL LANJEWAR 14th Jan, 2020

Hello,

Let, the work done by P be p

and the work done by Q and R together be x

So, from first condition, p = 2x

All three can do work in 21 days.

So, 21 [ ( 1 / 2x ) + ( 1 / x ) ] = 1

So, 21 ( 3x / 2 x^2 ) = 1

So, 2x = 3 x 21

So, x = 63 / 2

So, x = 31.5 days.

So, Q and R can do the work together in 31.5 days

Best Wishes.

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