A and B can finish a job in 10 days and 5 days, respectively. They worked together for 2 days, after which B was replaced by C, and the job was finished in the next 3 days. In how many days will C alone finish 50% of the job?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 15.
LCM(10, 5) = 10
The efficiency of A = 10/10 = 1 units
The efficiency of B = 10/5 = 2 units
Work done in 2 days = 2 × 3 = 6 units
Remaining work = 10 - 6 = 4 units
Now, A and C together finish 4 units in 3 days
A's 3 days' work = 3 units
Work done by C = 4 - 3 = 1 unit
So, the efficiency of C = 1/3 units
Time taken by C to cover 50% of the work = = 15 days