A water tank can be filled in 29 minutes by using 23 pipes of the same capacity. In how many minutes (rounded off to two decimal places) will the water tank be filled if we use 47 pipes of the same capacity as above?

Correct option is C

​Given:

Time to fill the tank with 23 pipes = 29 minutes

We need to find the time to fill the tank with 47 pipes.

Formula Used:

The time taken to fill the tank is inversely proportional to the number of pipes used. This can be expressed as:
​$$\text{Time} \propto \frac{1}{\text{Number of pipes}}$$​​

Solution:

Let the time taken with 47 pipes be t minutes. Using the formula:

​$$\frac{T_1}{T_2} = \frac{N_2}{N_1}$$​​
Where:

​$$T_1 =$$​29 minutes (time for 23 pipes)

​$$N_1 =$$​23 pipes (initial number of pipes)

​$$T_2 =$$​t minutes (time for 47 pipes)

​$$N_2 = 4$$​7 pipes (new number of pipes)

Substitute the given values into the formula:
t =$$\frac{29 \times 23}{47}$$​​

t = $$\frac{667}{47} = 14.19 \text{ minutes (rounded to two decimal places)}$$​​

The water tank will be filled in 14.19 minutes using 47 pipes.