At the beginning of 2010, 60% of the population of Town X lived in the south and the rest lived in the north. During 2010, the population of Town X grew by 5.5%. If the population in the south grew by 4.5%, by how much did the population in the north grow?
Choose the correct choice from the following options:
A) 1%
B) 3.5%
C) 6.5%
D) 7%
E) 13.75%
Ratio of population - South:North :: 60%:40% = 3:2   Mean growth = 5.5%   South Growth: 4.5%   North Growth = ??   South-------------Average--------------North   4.5% __(2n)_____5.5%_____(3n)_____??   Since:   4.5 + 2n = 5.5   n = 1/2 (this is the multiplier of the ratio)   Therefore:   North = 5.5 + 3n   North = 5.5 + 3(0.5) = 7%   ANSWER:7%
<result>D</result>
At the beginning of 2010, 60% of the population of Town X lived in the south and the rest lived in the north. During 2010, the population of Town X grew by 5.5%. If the population in the south grew by 4.5%, by how much did the population in the north grow?