# 60 workers can build a room in 50 days. But on the interval of 10 days

A. 60

B. 55

C. 75

D. 65

### Right Answer is: D

#### SOLUTION

Total work = 60 ×50 = 3000 units

Work completed in first 10 days = 60×10 = 600

Now 5 workers left the work, so now only 55 workers will work.

Work completed in next 10 days = 55×10 = 550

We will repeat this process till our total work is finished

⇒ 50 ×10 = 500 units

⇒ 45 ×10 = 450 units

⇒ 40 ×10 = 400 units

⇒ 35 ×10 = 350 units

Total work completed in first 60 days = 600 +550 +500 +450 +400 + 350 = 2850 units

Remaining work = 3000 – 2850 = 150 units

So, work completed in next 10 days =30 ×10 = 300 units

But only 150 units work in remaining, so workers will take only 5 days only

So total days = 60+5 = 65 days

60 workers can build a room in 50 days. But on the interval of 10 days