A rectangular container 100 cm by 40 cm by 45 cm was 30% filled with water. A tap was turned on to fill it up with water at a rate of 6 ℓ/min. Every 10 seconds after the tap was turned on, an iron ball of volume 600 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% - 30%
= 70%
Volume of space in the container
= 70% x 100 x 40 x 45
=
70100 x 100 x 40 x 45
= 126000 cm
3 1 ℓ = 1000 mℓ
6 ℓ = 6 x 1000 = 6000 mℓ
Number of sets of 10 seconds in 1 min
= 60 ÷ 10
= 6
Water flowed in every 10 seconds
= 6000 ÷ 6
= 1000 mℓ
Total volume added for every 10 seconds
= 1000 + 600
= 1600 cm
3 Number of sets of 1600 cm
3= 126000 ÷ 1600
= 78 r 1200
After the last iron ball is added, 1200 cm
3 of water will flow into the tank so that the container is 100% filled with water.
Number of iron balls added = 78
Answer(s): 78