Question

Two taps can fill an empty tank in 20 minutes and 30 minutes respectively. A third pipe can
drain a full-tank in 15 minutes. If all three pipes are opened at the same time. How long will it
take to fill an empty tank?​

Answer 1

Answer:

60 minutes or 1 hour

Step-by-step explanation:

let the name of the taps be A, B & C respectively

now

a/q

A can feel the tank in 20 minutes

B """"""""""""""""""""" 30 minutes

C can drain the tank in 15 minutes

so,

let the volume of the tank be

60 liters i.e. LCM of the time taken bye all the pipes

now

efficiency = volume/ time taken

so

efficiency of each pipe =

A = 60/20 = 3

B = 60/30 = 2

C = 60/15 = 4

Now

A&B can together feel the tank with an efficiency of 5 i.e. (3+2)

but C can drain the tank with an efficiency of 4

so the total efficiency of all the 3 taps together will be 5 - 4 = 1

now,

we know that

total time taken = volume / efficiency

when all the taps are open together the tank will will filled in =>

60/1 = 60 minutes or 1 hour ( answer)

Answer 2

Answer:

60

Step-by-step explanation:

1÷20+1÷30-1÷15=3+2-4/60 = 60