Question

A and B together can complete a piece of work in 12 days. A alone can complete in 20 days. If B does the work only half a day daily, then in how many days A and B together will complete the work ? 

(a) 10 days 

(b) 20 days 

(c) 11 days 

(d) 15 days

Answer 1

Correct option (d) 15 days

Explanation:

(A+B)’s one day work = 5 units.

A’s one day work = 3 units

B’s one day work = 2 units

B’s half day work = 1 units

Now, (A+B)’s work/day= 3 + 1 = 4 unit

Work done by (A+B) in = 60/4

= 15 days