CMA Foundation · Fundamentals of Business Mathematics and Statistics · Ratios, Variations and Proportions
A contractor's 20 men working 8 hours a day can build 120 metres of road in 15 days. How many days will 30 men working 6 hours a day need to build 180 metres of road at the same efficiency?
They need 20 days. The first team uses 20 × 8 × 15 = 2,400 man-hours for 120 m, which is 20 man-hours per metre. For 180 m, 3,600 man-hours are needed, and 30 men at 6 hours give 180 per day, so 20 days.
- A15
- B20Correct
- C18
- D12
Explanation
Work is proportional to men × hours × days. Men-hours per metre: 20×8×15/120 = 20. For 180 m we need 180×20 = 3,600 man-hours. Daily capacity = 30×6 = 180, so days = 3,600/180 = 20. Option 15 ignores the reduction in hours per day.
Did you get it right without looking?
One question tells you little. A timed set on Ratios, Variations and Proportions shows your real accuracy, how long you take and where you lose marks.
More Ratios, Variations and Proportions questions
- If 4, x and 25 are in continued proportion with x positive, and the mean proportional x is the second term, what is the value of (x + 4) : (…
- The time taken to complete a job by a team varies inversely with the number of workers. If 12 workers complete a job in 15 days, how many da…
- A sum of ₹7,200 is to be divided among Arun, Bala and Chitra so that Arun's share : Bala's share = 2 : 3 and Bala's share : Chitra's share =…
- The ratio 5:8 is to be made equal to a ratio in proportion with 35:k. Find k.
- The monthly electricity cost C of a factory varies jointly with the number of machines M and the hours H run per day. When 8 machines run 6 …
- The monthly incomes of Sunil and Tarun are in the ratio 5:4 and their expenditures are in the ratio 3:2. If Sunil saves ₹4,000 and Tarun sav…