SOLUTION: I would like help with the following problem.... Between 1980 and 1990 the population of Columbus grew 12%. a) Fill in the blank.. If the 1980 population was P, then the 1990 pop

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Question 69347: I would like help with the following problem....
Between 1980 and 1990 the population of Columbus grew 12%.
a) Fill in the blank.. If the 1980 population was P, then the 1990 population was _______ my answer is P+(P*.12)
b) The 1990 Population was 632910. Write an equation and find the 1980 population
______________________________ P=______________
my equation P=632910-(P*.12) but now I'm lost

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
You have the first problem down. If you know the population in 1990, in both algebraic and numerical form, then you could find the population in 1980. The population in 1990 equals (according to part a) P+(P*.12) then we can find P (the population in 1980.
Population in 1990:+P%2BP%2A.12=632910 add P and .12P
%28cross%281.12%29P%29%2Fcross%281.12%29=632910%2F1.12Divide both sides by 1.12
P=565098.21Note: the decimal part is a result of division and not actual result (cant have a fifth of a person), so you might want to round.
By the way you have the right idea for part b, you just subtracted .12P instead of adding it. Adding it to P allows you to isolate P.