Multiple choice

On nth day, n persons work (where n = 1, 2, 3, …..). This means that on first day, only one person works; on second day, 2 persons work, and so on. If the work is completed in 25 days, how many days does it take to complete the same work by a team of 25 people, if they work regularly?

  1. 9

  2. 13

  3. 12

  4. 15

  5. 16

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total work = sum of 1+2+3+...+25 = (25 * 26) / 2 = 325 person-days. If 25 people work regularly, time = 325 / 25 = 13 days.