Question

A boy is given rich diet and gains $15\%$ in weight. He is then put on a poor diet and loses $20\%$ in weight. On the whole the boy will

• A. lose $5\%$ weight
• B. lose $8\%$ weight
• C. lose $10\%$ weight
• D. remain the same

Answer 1

The correct option is B lose $8\%$ weight

Let his actual weight be x kg.
In the first case, his weight becomes 115% x
In the second, it becomes 80% of 115% x
$=\frac{80}{100}\times \frac{115}{100}x=92\%x$
He loses 8% of his actual weight.