Water flows into a container through Tap M and flows out of the container through Tap N. The capacity of a container is 42 litres. When only Tap M is turned on, the container is completely filled in 12 minutes. When only Tap N 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 N by the time the container is 35 filled with water? Express your answer in litres.
(a)
Tap M :
12 min → 1 container
1 min →
112 container
13 hour =
13 x 60 = 20 min
Tap N:
20 min → 1 container
1 min →
120 container
Tap M and Tap N:
1 min →
112 -
120 =
560 -
360 =
130 container
1 container →
301 = 30 min
90% container → 90% x 30 = 27 min
(b)
Time taken to fill
35 of the container
1 container → 30 min
35 container → 30 x
35 = 18 min
Volume that flows out per min
=
120 container
=
120 x 42
= 2.1 ℓ
Volume of water that flowed out through Tap N in 18 min
= 18 x 2.1
= 37.8 ℓ
Answer(s): (a) 27 min; (b) 37.8 ℓ