Challenger App

No.1 PSC Learning App

1M+ Downloads
A and B can separately do a piece of work in 6 days and 12 days respectively. How long will they together take to do the work ?

A8 days

B6 days

C5 days

D4 days

Answer:

D. 4 days

Read Explanation:

total work = lcm(6, 12) = 12 efficiency of A = 12/6 = 2 efficiency of B = 12/12 = 1 Time taken by both of them to do the work = total work/ total efficiency = 12/(2 + 1) = 4 days


Related Questions:

Three taps A, B and C can fill a tank in 10, 18 and 6 hours, respectively. If A is open all the time and B and C are open for one hour each alternatively, starting with B, the tank will be full in:
Nitin can do a piece of work in 7 hours. Pravin can do it in 21 hours. With the assistance of Rishi, they completed the work in 3 hours. In how many hours can Rishi alone do it?
If 45 persons can complete a work in 18 days, working 8 hours a day, then how many persons are required to complete two-thirds of the same work in 20 days, working 9 hours a day?
എ, ബി എന്നീ രണ്ട് പൈപ്പുകൾക്ക് യഥാക്രമം 20, 30 മിനിറ്റുകൾ കൊണ്ട് ഒരു ടാങ്ക് നിറയ്ക്കാനാകും. രണ്ട് പൈപ്പുകളും ഒരുമിച്ച് ഉപയോഗിച്ചാൽ, ടാങ്ക് നിറയാൻ എത്ര സമയമെടുക്കും?

Pipes A and B can fill a tank in 12 h and 18 h, respectively, whereas pipe C can empty the full tank in 8 h. A and B opened for 4124\frac{1}{2} h and then closed. C alone will empty the tank in (in h):