a city water supply tank has two inlet pipes x and y which can fill it in 20 and 30 hours respectively. and an outlet pipe z which can empty a full tank in 40 hours if the tank is empty and the taps are opened in succession for 1 hour each, and the process continues, in how many hours the tank get filled?
Answers
Answer:
Let the capacity of the tank be 60 units (LCM of 15, 20 & 30).
Pipe A fills =
15
60
=4 units / hour
Pipe B fills =
20
60
=3 units / hour
Pipe A fills =
30
60
=2 units / hour
(A + B + C)'s together per hour work = (4+3−2)=5 units/hour
Time taken by all three to fill an empty tank =
5
60
=12 hours.
Answer:
51 3/7
Step-by-step explanation:
Let pipe X and Y can fill the tank in 20 hours and 30 hours.
In 1 hour, X and Y can fill the 1/20 and 1/30 of tank's capacity.
Let pipe Z can empty the tank in 40 hours, In 1 hour Z can empty 1/40 of tank's capacity.
while X and Y filling the tank from empty in successive hours but Z emptying the tank in next hour.
In 2 hours , Both X and Y can fill -
1/20 + 1/30 = (20+30)/(20*30) = 50/600 =1/12 (of tank's capacity)
In 3rd hour, Z empties
1/12 - 1/40 = (40-12)/(12*40) = 28/480 =7/120
Each 3 hours the 7/120 of tank's capacity is filled.
Time required for completing Full tank , (120/7)*3 =360/7 =51(3/7).