Question

A pineapple costs Rs. $7$ each. A watermelon costs Rs. $5$ each. $X$ spends Rs. $38$ on these fruits. The number of pineapples purchased is

• A. $2$
• B. $3$
• C. $4$
• D. Data inadequate

Answer 1

Answer: (C)

$4$

Let the number of pineapples and watermelons be $x$ and $y$ respectively.
Then, $7x+5y=38$ or $5y=(38-7x)$ or $y=\frac{38-7x}{5}$.
Clearly, $y$ is a whole number, only when $(38-7x)$ is divisible by $5$.
This happens when $x=4$.