Discussion of Question with ID = 080 under Time-and-Work

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Question

A can finish a work in 10 days. B can do the same work in 5 days. They work together for 3 days. The fraction of work that is left is?

A

${1/10}$.

B

$1{1/10}$.

C

${1/9}$.

D

${2/11}$.

Soln.
Ans: a

They together finish $1/10 + 1/5$ work in a day. In 3 days they finish 3 × $(1/10 + 1/5)$ work, which is $45/50$. So the un-finished work is 1 - $45/50$ = ${1/10}$.


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