A rectangular tank 120 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 10 seconds after the tap was turned on, an iron ball of volume 100 cm3 was added to the tank. How many iron balls of the same volume would there be in the tank when the tank is 100% filled with water?
Percentage of volume of space to be filled
= 100% - 20%
= 80%
Volume of space in the tank
= 80% x 120 x 60 x 44
=
80100 x 120 x 60 x 44
= 253440 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 + 100
= 1100 cm
3 Number of sets of 1100 cm
3= 253440 ÷ 1100
= 230 r 440
After the last iron ball is added, 440 cm
3 of water will flow into the tank so that the tank is 100% filled with water.
Number of iron balls added = 230
Answer(s): 230