A fruit seller buys 240 apples for Rs. 600. Some of these apples are rotten and are thrown away. He sells the remaining apples at Rs. 3.50 each and makes a profit of Rs. 198. The % of apples thrown away are ?

Answer: Option B

Let the number of bad apples = x
Cost price of (240 - x) apples = Rs. 600
Selling Price of (240 - x) apples
= Rs. 3.50 × (240 - x)
According to the question,
⇒ 3.50 × (240 - x) - 600 = 198
⇒ x = 12
So, % of apples thrown away are
$$\begin{array}{rl}& x\%=\frac{12}{240}\times 100\%\\ & =5\%\end{array}$$

Alternate :
Selling price of apples
= 600 + 198 = 798
Number of apples sold
$$\begin{array}{rl}& =\frac{798}{3.50}=228\\ & \%\text{ of apples thrown}\\ & \text{ = }\frac{240-228}{240}\times 100\\ & =\frac{12}{240}\times 100\\ & =5\%\end{array}$$