#1 (7.5 x 10 5) / (2.5 x 10 2) = 3.0 x 10 3
#2 Wavelength of UV radiation = .0000001 m
#3 Population of the world = 6 x 10 9 people
#4 Ratio of Earth diameter to diameter of a carbon atom = 1 x 10 7 / 1 x 10 -10 = 1 x 10 17