IBPS SO Prelims Exam Model Paper 3

Given:
Pipe A can fill the reservoir in 25 minutes
Pipe B can fill the reservoir in 30 minutes
Concept:
Let, Pipe A can fill a tank in x hrs
⇒ Pipe A can fill a tank in 1 hr =

1

x

Calculation:
Pipe A can fill the reservoir in 1 minute =

1

25

Pipe B can fill the reservoir in 1 minute =

1

30

∴ Pipe (A + B) can fill the reservoir in 1 minute = (

1

25

+

1

30

) =

(6+5)

150

=

11

150

When waste pipe open Pipe A and B together fill the reservoir in 1 minute =

1

25

According to the question,
(

11

150

) - (

1

25

)
⇒

(11−6)

150

⇒

5

150

⇒

1

30

∴ The time waste pipe takes to empty the reservoir is 30 minutes.