Practice Test Discussion

'A' is thrice as good a workman as 'B' and so takes 60 days less than 'B' for doing a job. The time in which they can do the job together is

[LIC (AIO), 2012]

30 days

60 days

$22 \frac{1}{2}$ days

45 days

None of the above

Explanation

Let A can complete the work in x days and B in 3x days.

=3x-x=60

=2x=60

⇒ x=30 days

A can finish the work in 30 days and B can finish the same work in 90 days.

∴ in 1 day (A+B) can complete. $\frac{1}{30} + \frac{1}{90} = \frac{4}{90}$ ^th of the work

∴(A+B) can finish the complete work in $= \frac{90}{4}$ $o r 22 \frac{1}{2} d a y s$

Hence option C is the correct.

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