### My Scooty gives an average of 40 kmpl of petrol. But after recent filling at the new petrol pump, its average dropped to 38 kmpl. I investigated and found out that it was due to adulterated petrol. Petrol pimps add kerosene, which is $\frac{2}{3}$ cheaper than petrol, to increase their profits. Kerosene generates excessive smoke and knocking and gives an average of 18 km per 900 ml. If I paid Rs. 30 for a litre of petrol, What was the additional amount the pump-owner was making?

**A.** Rs. 1.75

**B.** Rs. 1.80

**C.** Rs. 2

**D.** Rs. 2.30

## Show Answer

###
Answer-C

Solution-

__Solution(By Apex Team)__

Let x ml of kerosene be there in 1 litre mixture.
Then, quantity of petrol in 1 litre mixture = (1000 – x) ml
$\begin{array}{l}\therefore\frac{40}{1000}(1000-x)+\frac{18}{900}x=38\\
\Rightarrow\frac{x}{25}-\frac{x}{50}=2\\
\Rightarrow\frac{x}{50}=2\\
\Rightarrow x=100\end{array}$
So, 1 litre mixture has 900 ml petrol and 100 ml kerosene.
Cost of 1 litre petrol = Rs. 30
Cost of 1 litre kerosene
$\begin{array}{l}=\text{ Rs. }\left[\left(1-\frac{2}{3}\right)\times30\right]\\
=\text{ Rs. }10\\
\text{Coast of 1 litre mixture}\\
=\text { Rs. }\left(\frac{30}{1000} \times 900+\frac{10}{1000} \times 100\right) \\
=\text { Rs. } 28
\end{array}$
∴ Additional amount earned by pump-owner
= Rs. (30 – 28)
= Rs. 2