Question

A person on a special diet containing 20% of fat gained 5 kg in a month. If his diet had 30% fat, then how much weight would he have gained?

• A. 2.5 kg
• B. 5 kg
• C. 7.5 kg
• D. 15 kg

Answer 1

The correct option is C 7.5 kg

If the intake of fat increases, then the person's weight will also increase.

$\therefore$ This is a case of direct proportion.
Using the formula for direct proportion,
$\frac{\text{Percentage of fat}}{\text{Increase in weight}}=\text{constant}$
$\Rightarrow \frac{20}{5}=\frac{30}{\text{Increase in weight}}$
$\therefore$ Increase in weight = $\frac{5}{20}\times 30$
= 7.5 kg