Question

When the air-conditioner is on, a typist can type X pages per hour. However, when the air-conditioner is off, she can type at $65\%$ of the earlier efficiency (when the air-conditioner is on). How many hours would she take to type out 575 pages when the air-conditioner is off?

• A. 375.4 X
• B. 884.6 X^–1
• C. 454.3 X^–1
• D. None of these

Answer 1

The correct option is B 884.6 X^–1

Let X=100, Then when AC is off, speed = 65 pages per hour.

Thus to type 575 pages, she takes $\frac{575}{65}=8.84$ pages per hour. Answer is option (b

Alternatively:
When the air-conditioner is off, 0.65X pages are typed per hour. 575 pages will be typed in

$\frac{575}{0.65X}=884.6X^{-1}$