‘A’ completes a work in 10 days, while ‘B’ and ‘C’ complete it in 12 and 15 days respectively. In how many days can ‘A’, ‘B’ and ‘C’ together complete the work ?
[amp_mcq option1=”3″ option2=”4″ option3=”5″ option4=”6″ correct=”option2″]
This question was previously asked in
UPSC CAPF – 2009
Combined daily work rate = 1/10 + 1/12 + 1/15.
Finding a common denominator (LCM of 10, 12, 15 is 60):
Combined rate = (6/60) + (5/60) + (4/60) = 15/60 = 1/4.
They complete 1/4 of the work per day.
Time taken to complete the whole work = 1 / (Combined rate) = 1 / (1/4) = 4 days.