give the full solution
4 pipes fill a cisern in 15,20,30 and 60 hrs .The first was opened at 6 am,the second at 8am,and the thrid at 10 am and the fourth at noon .When will the reservoir be full?
-
UP 0 DOWN 0 0 4
4 Answers
49let the pipes be A, B , C and D which can fill the tank in 15, 20, 30 and 60 hrs...
in 1 hr,
only A can fill 1/15 part of tank, B = 1/20 part, C = 1/30 part and D = 1/60 part...
from 6 am to 8 am,
part of tank filled in 1 hr=1/15
total part filled=2/15
part left=13/15
49from 8 am to 10 am,
part filled in 1 hr=1/15+1/20=7/60
total part filled=14/60=7/30
part left=13/15-7/30=19/30
49from 10 am to noon,
part filled in 1 hr=1/15+1/20+1/30=9/60=3/20
total part filled=6/20=3/10
part left=19/30-3/10=10/30=1/3
49from noon onwards,
part filled in 1 hr=1/15+1/20+1/30+1/60=10/60=1/6
time taken to fill up 1/3rd tank=1/3/1/6=2hrs.
so time in which tank is filled up=2 pm
