Question

20 men can complete a work in 15 days. They started work together and after every 5 days 2 men left the work. In how many days 90% of the work will be complete?
1. 15 days
2. 18 days
3. 20 days
4. 21 days

Answer 1

Correct Answer - Option 1 : 15 days

Given:

20 men can complete a work in 15 days.

Formula used:

Work = Efficiency × Time

Calculation:

Total work = 20 × 15 unit

⇒ 300 unit

Now, 90% of 300 units = (90/100) × 300 unit

⇒ 270 unit

First 5 days work by 20 men = 20 × 5 unit

⇒ 100 unit

Followed 5 days work by 18 men = 18 × 5 unit

⇒ 90 unit

Followed 5 days work by 16 men = 16 × 5 unit

⇒ 80 unit

Total work in 15 days = (100 + 90 + 80) units

⇒ 270 units

∴ 90% of the work is completed in 15 days.