# Algebra

posted by .

I need to find the future population using the model P=42+20ln(11t+1)
t= time in years
I need to find when it will be 180. I have my work below, but I am stuck. The answer I get is not right, it will not add up to 180. Maybe I am wrong some where.

P=42+20ln(11t+1)
180=42+20ln(11t+1)
-42 -42
(138/20)=(201n(11t+1)/20)
6.9=1n(11t+1)
e(6.9)=e^ln(11t+1)
e(6.9)=11t+1
-1 -1
[e(6.9)-1/11]=(11t/11)
t=[e(6.9)-1/11]

• Algebra -

When you divide by 11, don't you need to divide e^6.9 by 11 also?

## Similar Questions

how do you find the isoperimetric quotient of an n sided figure?
2. ### Math

I need to find the value of x. 5(x-4) = 3(x+8) Trying to help my niece and haven't done this stuff for 20 years. :) 5(x-4) = 3(x+8) 5x - 20 = 3x + 24 5x - 3x = 20 + 24 2x = 44 x = 22 I hope this brings back the algebra you studied …
3. ### religions

i need to make a model of any famous mosque in the world first, i need help finding pictures of different mosques to see which one would be easy to work with (i need a nice picture, maybe 3D, so i can copy it and build my model according …
4. ### algebra

2. The level of thorium in a sample decreases by a factor of one-half every 2 million years. A meteorite is discovered to have only 8.6% of its original thorium remaining. How old is the meteorite in millions of years?
5. ### pre-calc

The city planners of bakersfield, CA are studying the current and future needs of the city. The sewage system they have in place now can support 300,000 residents. The current population of the city is 180,000, up from 122,000 eight …
6. ### Pre-Calc (Follow-up with Bob Pursley)

For the below problem, I solved it as you suggested and got k=.0486 When I did 300,000 = 122,000e^.0486t I got about 18.5 years for when the sewer system would need to be updated. Next, for how many people will the new system have …
7. ### Algebra

I'm really stuck on these 2. Can you please explain the work clearly so that I can understand and find the answer easily, if already not given. Need help with these 2 please-- 19. Nancy invests \$100 in one account for 10 years at a …
8. ### Exponential model

Hi, I have a exponential model of P = 5.3 x (1.11)^t. I need to use this model to predict when a bird population will first exceed 500 pairs, so P is the number of pairs and t is the year. I have already come to an answer of 44 years …
9. ### College Algebra

The population of the Earth is approximately 6 billion people and is growing at an annual rate of 1.9%. Assuming a Malthusian growth model, find the world population in 45 years. (Round your answer to one decimal place.)