Multiple choice

240 men started working on a project which is supposed to be completed in 10 days. But starting from the second day, two men left the project every day till the 10th day. What is the percent of work which will be left undone after 10 days?

  1. 2.5%

  2. 3.25%

  3. 2.75%

  4. 3.75%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total work = 240 * 10 = 2400 man-days. Work done: Day 1 = 240, Day 2 = 238, ..., Day 10 = 222. This is an arithmetic progression with 10 terms. Sum = (10/2) * (240 + 222) = 5 * 462 = 2310. Work left = 2400 - 2310 = 90. Percent left = (90 / 2400) * 100 = 3.75%.

AI explanation

The total work is 240 men multiplied by 10 days, which equals 2400 man-days. Starting from the second day, two men leave every day, so the total man-days worked over the 10 days is 240 plus 238 plus 236 down to 222, which equals 2310 man-days. The remaining work is 2400 minus 2310, which equals 90 man-days. Calculating 90 out of 2400 gives 0.0375, which is 3.75 percent.

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