Water flows into a tank through Tap R and flows out of the container through Tap S. The capacity of a tank is 72 litres. When only Tap R is turned on, the container is completely filled in 12 minutes. When only Tap S is turned on, it takes
14 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 54% of the tank?
- How much water has flowed out through Tap S by the time the tank is 35 filled with water? Express your answer in litres.
(a)
Tap R :
12 min → 1 tank
1 min →
112 tank
14 hour =
14 x 60 = 15 min
Tap S:
15 min → 1 tank
1 min →
115 tank
Tap R and Tap S:
1 min →
112 -
115 =
560 -
460 =
160 tank
1 tank →
601 = 60 min
54% tank → 54% x 60 = 32.4 min
(b)
Time taken to fill
35 of the tank
1 tank → 60 min
35 tank → 60 x
35 = 36 min
Volume that flows out per min
=
115 tank
=
115 x 72
= 4.8 ℓ
Volume of water that flowed out through Tap S in 36 min
= 36 x 4.8
= 172.8 ℓ
Answer(s): (a) 32.4 min; (b) 172.8 ℓ