Question

A tank can be filled in 30 minutes. There is a leakage which can empty it in 60 minutes. In how many minutes can the tank be filled?

• A. 40 minutes
• B. 45 minutes
• C. 60 minutes
• D. 90 minutes

Hint:

Subtract the leak rate from the fill rate to get the net rate.

Answer 1

The Correct Option is C

Step 1: Filling rate of the tank \( = \dfrac{1}{30} \) tank per minute.
Step 2: Leak rate \( = \dfrac{1}{60} \) tank per minute.
Step 3: Net rate with the leak \( = \dfrac{1}{30} - \dfrac{1}{60} = \dfrac{2}{60} - \dfrac{1}{60} = \dfrac{1}{60} \) tank per minute.
Step 4: Time to fill \( = \dfrac{1}{1/60} = 60 \) minutes.
Answer: 60 minutes.