A swimming pool has a base 10 m by 12 m. Water evaporates from the pool at a constant rate of 10 liters per hour. Find the amount of water lost in one week and the change of depth in one week.
1 week = 7 days
1 week = 7 days ∙ 24 h = 168 h
1 m³ = 1000 ℓ
1 ℓ = 1 / 1000 m³ = 0.001 m³
10 ℓ = 10 / 1000 m³ = 0.01 m³
168 ∙ 10 ℓ = 1680 ℓ
The amount of water lost in one week = 1680 ℓ
1680 ℓ = 1680 / 1000 =1.68 m³
V = volume of water lost = 1.68 m³
d = the change of depth
V = 10 m ∙ 12 m ∙ d = 1.68 m³
120 ∙ d = 1.68 Divide both sides by 120
d = 1.68 / 120
d = 0.014 m = 14 mm
By the way 1 mm = 1 m / 1000 = 0.001 m