Question

A petrol pump delivers $4\dfrac{2}{5}$ litres of petrol per minute. How many minutes will to fill a tank holds $16\dfrac{1}{4}$ litres?
A) $4.45$ min
B) $3.69$ min
C) $3.25$ min
D) $5.25$ min

Answer 1

Hint:We have given the amount of petrol pumped in one minute so we can calculate the amount of time required to pump one litre of petrol. Now we just have to multiply the amount obtained for one litre with the given quantity of the petrol.

Complete step-by-step answer:
It is given that the petrol pump delivers $4\dfrac{2}{5}$ litres petrol in one minute.
We have to fill the tank with $16\dfrac{1}{4}$ litres of petrol.
First, we will convert the given fraction into the standard form.
We get,
$4\dfrac{2}{5} = \dfrac{{22}}{5}$
Similarly,
$16\dfrac{1}{4} = \dfrac{{65}}{4}$
Therefore, we have given that the pump delivers $\dfrac{{22}}{5}$ litres petrol in one minute.
Therefore, time taken by the pump to deliver one litre of petrol is:
$\dfrac{1}{{\dfrac{{22}}{5}}} \Rightarrow \dfrac{5}{{22}}$
Therefore, the time taken by the pump to deliver one litre of petrol is $\dfrac{5}{{22}}$ minutes.
Hence, to deliver $\dfrac{{65}}{4}$ litres of petrol the time taken is:
$\dfrac{5}{{22}} \times \dfrac{{65}}{4} = 3.69$
Thus, time taken by the pump to deliver $\dfrac{{65}}{4}$ litres of petrol is $3.69$ minutes.

So, the correct answer is “Option B”.

Note:Note that the given equation is actually a very simple correlation between the time taken by the pump and amount of petrol pumped. We just calculated the proportion related to the amount of petrol and time. We converted everything to the basic measures to calculate the final outcome.