A city’s current population is 1,000,000 people. It is growing at a rate of 3.5% per year. The equation P = 1,000,000(1.035)x models the city’s population growth where x is the number of years from the current year. In approximately how many years will the population be 1,200,000? Round to the nearest tenth.

Question

A city’s current population is  1,000,000 people. It is growing at a rate of 3.5% per year. The equation P = 1,000,000(1.035)x models the city’s population growth where x is the number of years from the current year. In approximately how many years will the population be 1,200,000?  Round to the nearest tenth.

aaronq · Answer

You use the equation given.

P = 1,000,000(1.035)x

P=is the population after x years

so, P=1,200,000=1,000,000(1.035)x

solve for x

anonymous · Answer

I got 5.3

aaronq · Answer

i got 1.2

anonymous · Answer

Its not 1 I thought it was too but its wronggg

aaronq · Answer

1,200,000/1,000,000=1.035x

1.2=1.035x

1.2/1.035=x

x=1.1594202898550725

they wanted rounded to the nearest tenth

x=1.2

anonymous · Answer

that's rounded to 1 ? I tried 1 it was wrong

aaronq · Answer

round to 1.2, tenth decimal place

anonymous · Answer

its 0

anonymous · Answer

that can't be right

aaronq · Answer

zero? lol it can't be zero, thats nonsense.

anonymous · Answer

zero!!

anonymous · Answer

http://calculator.tutorvista.com/math/405/rounding-to-tens-calculator.html

anonymous · Answer

That's what that said

anonymous · Answer

$$1.2=(1.035)^x\iff x=\frac{\ln(1.2)}{\ln(1.035)}$$

anonymous · Answer

1.1594

anonymous · Answer

and a calculator
the confusion was, the $x$ is in the exponent

anonymous · Answer

that's what I got ?

anonymous · Answer

your calculator is not working right http://www.wolframalpha.com/input/?i=ln%281.2%29%2Fln%281.035%29

anonymous · Answer

soo its 10 ?

anonymous · Answer

@satellite73