Originally Posted by

**peekay** In 1980 a town's population was 100,000. In 2007 it was 220,000. Estimate what the population will be in 2020 if its growth is exponential.

y=ka^x

220,000=100,000a^27

2.2=a^27

a = 1.0296

y=100,000(1.0296)^40

y=321,174.72

The population would be roughly 321,174.

Thats what I got for my answer, but the in the book its saying that y=100,000(**1.026**)^t is the equation that you would use and that 279,000 would be the population in 2020. Did I do something wrong with the years or is the answer in the back wrong?