A and B together can do a piece of work in 20 days. They worked for 8 days, and C completed the remaining in 4 days. How long will C alone take to do the whole work?
Show answer & explanation
Correct answer: B
Explanation
Given:
A + B completed the work together = 20 days
A and B worked together = 8 days
C completed the remaining work = 4 days
Formula:
Rate of work = 1 / time
A + B's 1 day rate = 1/20
Work done in 8 days = 8 × (1/20) = 2/5
Remaining work = 1 − 2/5 = 3/5
C completed 3/5 of the work in 4 days.
C's 1 day rate = (3/5) / 4 = 3/20
Time to complete the work = 1 / (3/20) = 20/3= 6.67 days