A alone can finish a work in 15 days. A works only for the first two days and the last two days. The rest work is done by B and the work is completed in 20 days. In how many days A and B together can finish the work?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. .
Given:
A can complete the whole work in 15 days.
A worked for the first and last 2 days.
B worked for 16 days.
Calculations:
Let the efficiency of A and B be x and y.
⇒ (2 + 2)x + 16y = 15x
⇒ 4x + 16y = 15x
⇒ 16y = 11x
⇒ x/y = 16/11
Total work = 15x = 15 × 16 = 240
Required time taken = 240/27 = 80/9 days