Pipes and Cistern - General Aptitude

Q1:

Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes, and 10 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P,Q and R respectively. What is the proportion of the solution R in the liquid in the tank after 3 minutes?

A
5
11

B
6
11

C
7
11

D
8
11

ANS:B -

6
11

Part filled by (A + B + C) in 3 minutes = 3 1 + 1 + 1 = 3 x 11 = 11 .
30 20 10 60 20
Part filled by C in 3 minutes = 3 .
10
Required ratio = 3 x 20 = 6 .
10 11 11