The tank below was 30% filled with water. Taps A and B were turned on at the same time. Water flowed from Tap A at the rate of 196 cubic cm per second, while Tap B at 100 cubic cm per second.

a) Find the volume of water in the tank before the taps were turned on.

b) How much time was needed to fill 40% of the tank?**Solution****Q(a)**

Water was filled up to 30% of the tank. Therefore volume of water in the tank is

80 cm x 40 cm x 30 cm x 30%

= 28 800 cubic cm

= 28.8 litres

**Answer: The volume of water in the tank before both taps were turned on was 28.8 litres.**

**Q(b)**

For the tank to be filled up to 40%, water is needed to fill it up by another 10% of the tank.

30% of the volume of the tank holds 28.8 litres.

10% will hold ----- 28.8 litres divided by 3 = 9.6 litres

Tap A had a rate of 196 ml per second, while Tap B 100 ml per second.

Net flow of water into the tank is therefore 196 ml per sec – 100 ml per sec = 96 ml per sec.

Time taken to fill up 9.6 litres -----

9.6 litres divided by 96 ml per sec

= 100 seconds

= 1 min 40 seconds.

**Answer: It takes 1 min 40 seconds to fill up to 40% of the tank.**

## No comments:

Post a Comment