Answer
$4.8\times10^5$ metric tons of water fell on the city.
$1.3\times10^8$ gallons of water fell on the city.
Work Step by Step
First let's calculate the volume of water that fell on the city:
$V = (6000 ~m)(8000 ~m)(0.01 ~m) = 4.8\times10^5 ~m^3$
Water has a mass of $10^3$ kg per $m^3$:
$mass = (4.8\times10^5 ~m^3)(10^3 ~kg/m^3) = 4.8\times10^8 ~kg$
$(4.8\times10^8 ~kg)(\frac{1 ~ton}{10^3 ~kg}) = 4.8\times10^5 ~tons$
$(4.8\times10^5 ~m^3)(10^3 ~L/m^3)(\frac{1 ~gal}{3.8 ~L}) = 1.3\times10^8$ gallons
