A rectangular container 80 cm by 60 cm by 44 cm was 20% filled with water. A tap was turned on to fill it up with water at a rate of 6 ℓ/min. Every 20 seconds after the tap was turned on, an iron ball of volume 100 cm3 was added to the container. How many iron balls of the same volume would there be in the container when the container is 100% filled with water?
Percentage of volume of space to be filled
= 100% - 20%
= 80%
Volume of space in the container
= 80% x 80 x 60 x 44
=
80100 x 80 x 60 x 44
= 168960 cm
3 1 ℓ = 1000 mℓ
6 ℓ = 6 x 1000 = 6000 mℓ
Number of sets of 20 seconds in 1 min
= 60 ÷ 20
= 3
Water flowed in every 20 seconds
= 6000 ÷ 3
= 2000 mℓ
Total volume added for every 20 seconds
= 2000 + 100
= 2100 cm
3 Number of sets of 2100 cm
3= 168960 ÷ 2100
= 80 r 960
After the last iron ball is added, 960 cm
3 of water will flow into the tank so that the container is 100% filled with water.
Number of iron balls added = 80
Answer(s): 80