Water flows into a container through Tap N and flows out of the container through Tap P. The capacity of a container is 60 litres. When only Tap N is turned on, the container is completely filled in 16 minutes. When only Tap P is turned on, it takes
13 hour for all the water to flow out. If both taps are turned on at the same time,
- How long does it take to fill 90% of the container?
- How much water has flowed out through Tap P by the time the container is 35 filled with water? Express your answer in litres.
(a)
Tap N :
16 min → 1 container
1 min →
116 container
13 hour =
13 x 60 = 20 min
Tap P:
20 min → 1 container
1 min →
120 container
Tap N and Tap P:
1 min →
116 -
120 =
580 -
480 =
180 container
1 container →
801 = 80 min
90% container → 90% x 80 = 72 min
(b)
Time taken to fill
35 of the container
1 container → 80 min
35 container → 80 x
35 = 48 min
Volume that flows out per min
=
120 container
=
120 x 60
= 3 ℓ
Volume of water that flowed out through Tap P in 48 min
= 48 x 3
= 144 ℓ
Answer(s): (a) 72 min; (b) 144 ℓ