Water flows into a tank through Tap A and flows out of the container through Tap B. The capacity of a tank is 42 litres. When only Tap A is turned on, the container is completely filled in 12 minutes. When only Tap B 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 42% of the tank?
- How much water has flowed out through Tap B by the time the tank is 35 filled with water? Express your answer in litres.
(a)
Tap A :
12 min → 1 tank
1 min →
112 tank
13 hour =
13 x 60 = 20 min
Tap B:
20 min → 1 tank
1 min →
120 tank
Tap A and Tap B:
1 min →
112 -
120 =
560 -
360 =
130 tank
1 tank →
301 = 30 min
42% tank → 42% x 30 = 12.6 min
(b)
Time taken to fill
35 of the tank
1 tank → 30 min
35 tank → 30 x
35 = 18 min
Volume that flows out per min
=
120 tank
=
120 x 42
= 2.1 ℓ
Volume of water that flowed out through Tap B in 18 min
= 18 x 2.1
= 37.8 ℓ
Answer(s): (a) 12.6 min; (b) 37.8 ℓ