Question

If P and Q together can do a job in 15 days, Q and R together can do it in 12 days and P and R together can do the same in 20 days, then in how many days will the job be completed, if all the three work together?

• A. 4 days
• B. 6 days
• C. 10 days
• D. 14 days

Answer 1

Answer:

C. 10 days

60 is the total work

4 and 5 and 3 are efficiency respectively

$\frac{work}{time} = \text{efficiency}$

so total efficiency together is 12

2(A+B+C)=4+5+3=12

(A+B+C)=12/2=6

so if all the three work together the no of days

=60/6=10 days