Time and Work Practice Test 1 with solutions

Question : 28 of 40

Marks: +1, -0

A can do a piece of work in 40 days. He starts working, but having some other engagements he drops out after 5 days. Thereafter B completes this work in 21 days. How many days would A and B take to complete this work working together?

15 days
16 days
17 days
11 days

Validate

Solution:

A's 5 days' work =

5 × 1/{40}

1/8

Remaining work =

1 - 1/8

7/8

, which is done by B in 21 days.
Hence, B's 1 day's work =

7/{8×21}

1/{24}

Now, (A + B)'s 1 day's work =

1/{40}+1/{24}

8/{120}

1/{15}

Hence, (A + B) will complete the work in 15 days.

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