A, B, and C can do a job working alone in 50, 75 and 20 days respectively. They all work together for 4 days, then C quits. How many days will A and B take to finish the rest of the job?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 ie 20.
LCM (50, 75, 20) = 300
A can do = 300/50 = 6 units/day
B can do = 300/75 = 4 units/day
C can do = 300/20 = 15 units/day
Each day work = 15 + 4 + 6 = 25 units/days
A and B’s 1 day work = 10 units
Therefore,
200/10 = 20 days