How to Calculate Successive Percentage Changes Faster Than a Calculator

Question 1

One tap can fill a pool in 8 hours and another can fill it in 12 hours. How long to fill the pool together?

MCQ

4.8 hours 6 hours 5 hours 5.2 hours

Question 2

Tap X fills a bucket in 20 minutes and Tap Y fills it in 5 minutes. If both work together, the time taken is:

MCQ

2 minutes 8 minutes 4 minutes 6 minutes

Question 3

Pipe A can fill a tank in 10 hours and Pipe B can fill it in 15 hours. How long will they take to fill the tank together?

MCQ

6 hours 12 hours 8 hours 5 hours

Question 4

Working together, A and B can complete a task in 12 days. If A alone takes 20 days, how many days will B take alone?

MCQ

30 days 25 days 35 days 40 days

Question 5

Pipe A fills a tank in 40 minutes and Pipe B fills it in 60 minutes. What is the time taken to fill the tank together?

MCQ

30 minutes 24 minutes 20 minutes 22 minutes

Question 6

A cistern can be filled by two pipes in 12 minutes and 24 minutes respectively. How many minutes will it take to fill if both are open?

MCQ

10 minutes 6 minutes 9 minutes 8 minutes

Question 7

A tank is filled in 5 hours by Pipe A and 10 hours by Pipe B. How long will it take if both are opened together?

MCQ

2.5 hours 4 hours 3.5 hours 3.33 hours

Question 8

Two inlets fill a tank in 18 minutes and 9 minutes. If both are opened, the tank fills in:

MCQ

5 minutes 6 minutes 4 minutes 7 minutes

Question 9

If Pipe A fills a tank in 6 minutes and Pipe B fills it in 30 minutes, the time taken together is:

MCQ

5 minutes 7 minutes 4 minutes 6 minutes

Question 10

A man can do a piece of work in 15 days and his son can do it in 10 days. How many days will they take together?

MCQ

7 days 8 days 5 days 6 days