Complete question :
A heavy rainstorm dumps 1.0 cm of rain on a city 5 km wide and 8 km long in a 2-h period. How many metric tons (1 metric ton = 103 kg) of water fell on the city? (1 cm3 of water has a mass of 1 g = 10−3 kg.) How many gallons of water was this?
Answer:
4 * 10^5 metric tonne
Explanation:
Given that :
City dimension : 5km by 8km = 5*10^5 by 8*10^5 cm
Drop of rain = 1cm
Volume of rain within 2 hour period :
V = (5*10^5 * 8*10^5 * 1) cm³
V = 40 * 10^10 cm³
1cm³ = 1g
40 * 10^10 cm³ = 40 g
(40 * 10^10) * (10^-3) = 40*10^7 kg
1 metric tonne = 1 * 10^3 kg
x = 40*10^7 kg
x = (40 * 10^7) / 10^3
x = 40 * 10^(7 - 3) metric tonne
x = 40 * 10^4
x = 4 * 10^5 metric tonne