Question

A large tanker can be filled by two pipes a and b in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if b is used for half the time and a and b fill it together for the other half ? Option 1 : 15 min option 2 : 20 min option 3 : 27.5 min option 4 : 30 min

Answer 1

Solution:
parts filled by A in 1 min = 1/60
parts filled by B in 1 min = 1/40

parts filled together in 1 min = (1/60 + 1/40) = 1/24

if tank fills in x mins
then

0.5(x)*{ 1/24 + 1/40 } = 1
0.5(x) = 15
x = 30 mins

option 4 : 30 mins is the correct answer

Hope that helps !!!

Answer 2

☆Question ☆

A large tanker can be filled by two pipes a and b in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if b is used for half the time and a and b fill it together for the other half ? Option 1 : 15 min option 2 : 20 min option 3 : 27.5 min option 4 : 30 min.

☆Answer☆

In the attachment..