Discussion of Question with ID = 091 under Pipes-and-Cisterns

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Question

Three taps R, G and B are supplying red, green and blue colored inks into a tub. They can independently fill the tub in 6, 2 and 8 minutes. They are turned on at the same time. What is the ratio of blue ink after 3 minutes?

A

${3/19}$.

B

$1{2/9}$.

C

${1/7}$.

D

$2{6/7}$.

Soln.
Ans: a

Let the time taken by them to independently fill the tank be r, g and b minutes. Ink discharged by the blue tap is $3/b$. The total of all the inks is $3/r + 3/g + 3/b$. The ratio is ${1/b}/{1/r + 1/g + 1/b}$, which simplifies to ${rg}/{rg + gb + br}$ = ${3/19}$.


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