If the exponential equation of best fit is y= 2.9046(1.9798)^x, when will the population be more than 13 million?

Question

How would I figure this out?

I already determined the population in 30 days was 2,299,989,909 which is quite far from 13 million, but that gave me the number of days to figure out. How do I figure out when they give me the answer and I have to figure out the number of days?

Answer 1

y=2.9046(1.9798)^x
Solve for y=13. So:
13=2.9046(1.9798)^x
13/2.9046=1.9798^x
4.47566=1.9798^x
ln 4.47566=ln 1.9798^x=x ln 1.9798
x=2.1942355
The number of days, at that rate, would be 2.1942355
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Answer 2

except you want

2.9046(1.9798)^x = 13000000
x = 22.42

Answer 3

Thank you, but could you tell me how I would enter this into my calculator?

Answer 4

the same way you did it, but using the right value of 13,000,000 instead of 13.