A is thrice as productive as C. Together they can complete a job in 22.5 days. If B joins them after they have worked for 15 days then in how many days can they finish the rest of the job if B alone can do the job in 15 days?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 3
A's efficiancy/C's efficiancy = 3/1
Total work = 4 × 22.5 = 90
Efficiancy of B = (Total work)/(number of days taken by B) = (90)/(15) = 6
A and C work for 15 days, then B joins them
remaining work = 4 × 7.5 = 30
Time taken by A, B and C = (total work)/efficiancy = 30/(3 + 6 + 1) = 3