Water flows into a tank through Tap X and flows out of the container through Tap Y. The capacity of a tank is 76 litres. When only Tap X is turned on, the container is completely filled in 12 minutes. When only Tap Y 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 tank?
- How much water has flowed out through Tap Y by the time the tank is 25 filled with water? Express your answer in litres.
(a)
Tap X :
12 min → 1 tank
1 min →
112 tank
13 hour =
13 x 60 = 20 min
Tap Y:
20 min → 1 tank
1 min →
120 tank
Tap X and Tap Y:
1 min →
112 -
120 =
560 -
360 =
130 tank
1 tank →
301 = 30 min
90% tank → 90% x 30 = 27 min
(b)
Time taken to fill
25 of the tank
1 tank → 30 min
25 tank → 30 x
25 = 12 min
Volume that flows out per min
=
120 tank
=
120 x 76
= 3.8 ℓ
Volume of water that flowed out through Tap Y in 12 min
= 12 x 3.8
= 45.6 ℓ
Answer(s): (a) 27 min; (b) 45.6 ℓ