Multiple choice

Each one of five men independently can complete a work in 20 days. The work is started by one person. Next day one more person joins and every next day one more person joins. From the fifth day, five persons continued working as a team. In how many days, will the work be completed?

  1. 3

  2. 5

  3. 2

  4. 6

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

Each person can do 1/20 of the work per day. Day 1: 1 person completes 1/20. Day 2: 2 persons complete 2/20. Day 3: 3 persons complete 3/20. Day 4: 4 persons complete 4/20. After 4 days, total done = 10/20 = 1/2. Remaining 1/2 is done by 5 persons at 5/20 per day, taking 2 more days. Total = 6 days.