Question

A population of 80,000 toads is expected to shrink at a rate of 9.2% per year.

What will the toad population be in 20 years?
3632
7360
11,609
72,640

Answer 1

@AkashdeepDeb

Answer 2

Divide the population by the percent 80,000-9.2%=72640
Then divide your answer by 20 years'.

Answer 3

\(\Large P = 80,000(1 - 0.092)^t \)
\(\Large P = 80,000(0.908)^t \)
Put t = 20 in the above formula.

Answer 4

Thank you guys so much!

Answer 5

Anytime :)

Answer 6

Okay, so I got the answer 11, 609. Is that right? If not, could you possibly tell me what Im doing wrong so I can understand how to do it correctly.

Answer 7

You have the correct answer.

Answer 8

Okay, thank you ranga!

Answer 9

You are welcome.

Answer 10

I'm having a little trouble with this question.

In 2010, a city’s population was 1,405,233 and it was decreasing at a rate of 1.1%.

At this rate, when will the city’s population fall below 1,200,000?

in 2024
in 2027
in 2036
in 2049

Answer 11

@ranga

Answer 12

Similar formula as before but this time you have to solve for t.

\(\Large P = 1,405,233(1 - 0.011)^t\)
\(\Large P = 1,405,233(0.989)^t\)
\(\Large 1,200,000 = 1,405,233(0.989)^t\)

Solve for 't'.

Answer 13

\(\Large \frac{1,200,000}{1,405,233} = 0.989^t \)

Answer 14

Would the answer be in 2027?

Answer 15

I am getting a different answer.

Answer 16

Okay, let me retry this. I am thinking I made a mistake on my calculator that I am not catching.

Answer 17

\( \Large 0.8539509 = 0.989^t \)
\( \Large \log(0.8539509) = \log(0.989^t) = t\log(0.989) \)
\( \Large t = \frac{\log(0.8539509)}{\log(0.989)} = ? \)

Answer 18

Okay, so would the answer be in 2036?

Answer 19

You are just throwing out numbers.

Answer 20

No, I'm not. I keep coming up with either 2036 or 2027 on my calculator.

Answer 21

@PrincessLilian

Answer 22

I'm not really an expert on this topic :/

Answer 23

Okay, thanks anyways.

Answer 24

I can try to help?

Answer 25

Okay. That will work!

Answer 26

This is so confusing I can't do it :( I think you should try subtracting the population by the percent. Then keep doing that for each year.

Answer 27

Okay, thanks. Ill try that!

Answer 28

:) I'm so sorry that I couldn't help.

Answer 29

Its okay. No worries!

Answer 30

\(\Large t = \frac{\log(0.8539509)}{\log(0.989)} = ? \)

Answer 31

I just had my mom try to do it. She got 2024. Im coming up with two different answers and she is coming up with another answer.

Answer 32

In the above calculation, t is approx. 14 and so 2010 + 14 = 2024 is correct.

Answer 33

Okay great.