P and Q need 8 days to complete a work. Q and R need 12 days to complete the same work. But P, Q and R together can finish it in 6 days. How many days will be needed if P and R together do it?

Answer: 8
Explanation
Let work done by P in 1 day = p
work done by Q in 1 day =q
Work done by R in 1 day = r
p + q = 1/8 —(1)
q + r= 1/12 —(2)
p+ q+ r = 1/6 —(3)
(3) – (2) => p = 1/6 – 1/12 = 1/12
(3) – (1) => r = 1/6 – 1/8 = 1/24
p + r = 1/12 + 1/24 = 3/24 = 1/8
=> P and R will finish the work in 8 days.
This question appeared in Past Papers (4 times)
PPSC 5 Years Past Papers Subject Wise (Solved with Details) (2 times)
PPSC Excise and Taxation Inspector Past Papers and Syllabus (1 times)
This question appeared in Subjects (1 times)
MATHS MCQS (1 times)

Install this app on your device for quick access right from your home screen.