Time and Work Practice Test 2 with solutions

Question : 28 of 40

Marks: +1, -0

A and B can do a piece of work in 45 days and 40 days respectively. They began to do the work together but A leaves after some days and then B completed the remaining work in 23 days. The number of days after which A left the work was:

12 days
9 days
8 days
6 days

Validate

Solution:

B's 23 days' work =

{23}/{40}

Remaining part of work = 1 -

{23}/{40}

{17}/{40}

which has been already done by A and B.
(A + B)'s 1 days' work =

1/{45}+1/{40}

{17}/{360}

Hence, time taken by (A + B) to do the same work =

{{17}/{40}}/{{17}/{360}}

{17}/{40} × {360}/{17}

= 9 days.

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