Question

A typing work is done by two persons A and B. A and B together can type a booklet in 4 hours, but A alone takes 12 hours to type the booklet. How many hours required for B to type the booklet?

• A. 3 hours
• B. 4 hours
• C. 5 hours
• D. 6 hours

Hint:

For combined work, subtract individual rates to find the unknown worker’s efficiency.

Answer 1

The Correct Option is D

Concept: Work rate method: Work rate = Work per hour. Explanation: A + B together = $\frac{1}{4}$ work/hour A alone = $\frac{1}{12}$ work/hour So, B’s rate: \[ \frac{1}{4} - \frac{1}{12} = \frac{3 - 1}{12} = \frac{1}{6} \] Thus, B alone takes 6 hours.