Water flows into a tank at the rate of 50 ℓ per minute. After 16 min, the tap is turned off and the tank is 0.8 filled with water.

1. How much more water is needed to fill it to the brim?
2. The water in the tank is then poured into containers each 1.2 m long, 0.4 m wide and 16 cm high. What is the minimum number of containers needed?

(a)
0.8 =  ⁴₅

Let 5 u be the total volume of water when the tank is completely filled.

Volume of water in the tank
= 50 x 16
= 800 ℓ

4 u = 800

1 u = 800 ÷ 4 = 200

Volume of water to fill the tank to the brim
= 5 u - 4 u
= 1 u
= 1 x 200
= 200 ℓ

(b)
1 m = 100 cm
1.2 m = 120 cm
0.4 m = 40 cm

Volume of each container
= 120 x 40 x 16
= 76800 cm³

Volume of water in the tank = 800 ℓ

1 ℓ = 1000 mℓ
800 ℓ = 800000 mℓ

Number of containers needed
= 800000 ÷ 76800
= 10 r 32000

Minimum number of containers needed
= 10 + 1 
= 11

Answer(s): (a) 200 ℓ; (b) 11