Multiple choice

A and B can do a work in 15 and 10 days respectively. A and B started working together and after 3 days A quit. How many days did it take to complete the work?

  1. 5

  2. 8

  3. 10

  4. 14

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A's work rate=1/15 per day, B's=1/10 per day. Together they do (1/15+1/10)=1/6 per day. In 3 days, they complete 3/6=1/2 the work. Remaining half is done by B alone at 1/10 per day, requiring 5 days. Total time=3+5=8 days.