Question

Tick (✓) the correct answer:
A number decreased by $27\frac{1}{2}\%$ gives 87. The number is
(a) 58
(b) 110
(c) 120
(d) 135

Answer 1

(c) 120
Let the required number be x.
Then, we have: $x-27\frac{1}{2}\%$ of x=87
$\Rightarrow x-\frac{55}{2}\%$ of x=87
$\Rightarrow x-x\times \frac{55}{2}\times \frac{1}{100}=87$
$\Rightarrow x-\frac{11x}{40}=87$
$\Rightarrow \frac{29x}{40}=87$
$\Rightarrow x=87\times \frac{40}{29}$
$\therefore x=120$