Question 9 of 10 · Time & Work
Questionmedium
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NIMCET 2018

Two men and three boys can do a piece of work in ten days, while three men and two boys can do the same work in eight days. In how many days can two men and one boy do the work?

Answer View answer ▾

Answer: Option A — 12.5

Detailed Solution

1

10(2m + 3b) = 8(3m + 2b) gives 20m + 30b = 24m + 16b, so 4m = 14b and m = 3.5b.

2

Total work = 10(2m + 3b) = 10(7b + 3b) = 100b.

3

2 men and 1 boy do 7b + b = 8b per day, so they need 100/8 = 12.5 days.

✓ Check

3 men and 2 boys do 10.5b + 2b = 12.5b per day, and 8 x 12.5b = 100b, the same work.

⚠ Common trap

Do not assume one man equals two boys; the data give one man = 3.5 boys.

Quick tip

; work , rate days

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Time & Work — Preparation

This question tests your understanding of Time & Work, a key topic in the Quantitative Aptitude section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.

Time and work questions deal with how long one or more people, machines or pipes take to complete a task. The core idea is that if someone finishes a job in n days, they complete 1/n of the job each day. Questions involve people working together, joining or leaving partway, working on alternate days, efficiency comparisons, and wages shared in proportion to work done. Pipes and cisterns questions use the same logic and have their own page. The LCM method is the fastest approach for most questions. Take the total work as the LCM of the individual times, find each person's work per day, and the rest becomes simple division. This avoids messy fractions and makes problems with three or more workers much easier to handle. Practise the time and work questions below. Each solution shows the step-by-step working and the LCM shortcut where it helps.