Question

A car can travel 75 km in 3 litres of petrol. On a road trip, it travels at a speed of 50 km/h for 2 hours and then 75 km/h for the next 2 hours. How much money should be spent on petrol for this road trip if 1 litre costs ₹70?

• A. ₹700
• B. ₹1,000
• C. ₹680
• D. ₹650

Answer 1

The correct option is A ₹700

Given, a car can travel 75 km in 3 litres of petrol.

Distance travelled on the road trip = distance travelled at 50 km/hr + distance travelled at 75 km/hr

$\because \text{Distance}=\text{Speed}\times \text{Time}$
$\text{Distance covered}=50\times 2+75\times 2$
$\Rightarrow \text{Distance covered}=100+150$
$\Rightarrow \text{Distance covered}=250\text{km}$

We know that if distance increases, the consumption of petrol will also increase.

$\text{So, Distance}\left(x\right)\propto \text{Litres of petrol}\left(y\right)$
$\therefore \frac{x_1}{y_1}=\frac{x_2}{y_2}$

Given,
$x_1=75\text{km}$
$y_1=3\text{litres}$
$x_2=250\text{km}$
$\text{and}{y}_2=\text{litres of petrol consumed}$
$\Rightarrow \frac{75}{3}=\frac{250}{y_2}$
$\Rightarrow y_2=\frac{250\times 3}{75}=10\text{litres}$

Since, 1 litre of petrol costs ₹70
$\therefore \text{10 liters will cost}=10\times 70=₹700$