Question

Two pipes a and b can fill an empty tank in 10 hours and 15 hours respectively. Pipe c alone can empty the completely filled tank in 12 hours. First both pipes a and b are opened and after 5 hours pipe c is also opened. What is the total time (in hours) in which the tank will be filled?

Answer 1

Let the capacity of the tank be C.

Time taken by pipe A = 12 mins

Rate of filling tank by pipe A = C/12 per min

Time taken by pipe B = 18 mins

Rate of filling tank by pipe B = C/18 per min

When both the pipes are opened then the rate of filling tank by both pipes would be

= C/12 + C/18

= (3C + 2C) / 36

= 5C/36 per min

So, time taken when both are opened would be

= Capacity of tank / rate of both pipes combined

= C / (5C/36)

= 36/5

= 7.2 mins

☺️ hope it helps you ☺️

Answer 2

Answer:

3 hours

Step-by-step explanation:

= 5,10,30= 1/5 , 1/10, 1/30

= Take LCM of 5,10,30

= LCM = 30

= 1/30, 1/30, 1/30

= 1+1+1= 3

Answer= 3 hours