Water flows into a container through Tap J and flows out of the container through Tap K. The capacity of a container is 78 litres. When only Tap J is turned on, the container is completely filled in 12 minutes. When only Tap K 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 60% of the container?
- How much water has flowed out through Tap K by the time the container is 25 filled with water? Express your answer in litres.
(a)
Tap J :
12 min → 1 container
1 min →
112 container
13 hour =
13 x 60 = 20 min
Tap K:
20 min → 1 container
1 min →
120 container
Tap J and Tap K:
1 min →
112 -
120 =
560 -
360 =
130 container
1 container →
301 = 30 min
60% container → 60% x 30 = 18 min
(b)
Time taken to fill
25 of the container
1 container → 30 min
25 container → 30 x
25 = 12 min
Volume that flows out per min
=
120 container
=
120 x 78
= 3.9 ℓ
Volume of water that flowed out through Tap K in 12 min
= 12 x 3.9
= 46.8 ℓ
Answer(s): (a) 18 min; (b) 46.8 ℓ