A water tank can be filled in 19 minutes by using 39 pipes of the same capacity. In how many minutes (rounded off to two decimal places) will the water tank be filled if we use 23 pipes of the same capacity as above?​

Correct option is B

Given:

A water tank can be filled in 19 minutes using 39 pipes.

We need to find how many minutes it will take to fill the same water tank using 23 pipes.

Formula Used:

​$$\text{Time}_1 \times \text{Pipes}_1 = \text{Time}_2 \times \text{Pipes}_2$$​

Solution: 

​$$\text{Time}_1$$​ = 19 minutes (time with 39 pipes)

​$$\text{Pipes}_1$$​ = 39 (number of pipes in the first case)

​$$\text{Time}_2$$​ = ? (time with 23 pipes)

​$$\text{Pipes}_2$$​ = 23 (number of pipes in the second case)

Now, Using the formula

19 × 39 = x × 23

$$x = \frac{19 \times 39}{23}\\ \ \\x = \frac{741}{23} \approx 32.22 \, \text{minutes}$$​