Tutors Answer Your Questions about Exponential-and-logarithmic-functions (FREE)
Question 1163680: 1. A university invests $100,000 into an account that pays a 4.75% annual rate compounded continuously. Using the formula A=Pert, where A=the amount in the account after t years, P=principal invested, and r=the annual interest rate, how many years, to the nearest tenth, will it take for the university's investment to double?
b) to triple?
c) to quadruple?
Click here to see answer by ikleyn(52800)   |
Question 1164123: Question: A bone was found to contain 40% of the Carbon-14 that it contained when it was part ofa living animal. If the decay of Carbon-14 is exponential with an annual rate of decay of 0.0124%, how long ago did the animal die?
How far I got:
The amount lost was 60% or 0.6
Rate is -0.0124% or -0.000124
Equation created: 0.6 = 1e^-0.000124t | t is the number of years
I get an answer: -14694.5065 meaning the animal died 14695 year ago
Apparantly I am wrong by one digit, the answer being 1471 years.
Where did I insert the extra 0?
Thank you
Click here to see answer by solver91311(24713)  |
Question 1164123: Question: A bone was found to contain 40% of the Carbon-14 that it contained when it was part ofa living animal. If the decay of Carbon-14 is exponential with an annual rate of decay of 0.0124%, how long ago did the animal die?
How far I got:
The amount lost was 60% or 0.6
Rate is -0.0124% or -0.000124
Equation created: 0.6 = 1e^-0.000124t | t is the number of years
I get an answer: -14694.5065 meaning the animal died 14695 year ago
Apparantly I am wrong by one digit, the answer being 1471 years.
Where did I insert the extra 0?
Thank you
Click here to see answer by ikleyn(52800) |
Question 1164626: The function f(x) = 800(.5)^ x/60 models the account in pounds of a particular radioactive material stored in a concrete vault, where X is the number of years since the material was put into the vault. Find the amount of radioactive material in the vault after 130 years. Round to the nearest whole number.
Click here to see answer by Boreal(15235)  |
Question 1165573: A hypothetical function representing the concentration of a drug in a patientโs bloodstream over time ๐ก (in hours) is given as ๐(๐ก) = 5๐ก ๐ก2+1 .
(a) Construct a table of values. (Start from 0 to 9)
(b) Plot the points in a Cartesian plane (Again, construct your own cartesian plane on a separate graphing paper if the space provided is not enough) and connect them.
(c) What can you say about the function?
Click here to see answer by greenestamps(13200)  |
Question 1167965: An investment of $3000 earns 3.5% compounded semi- annually.
a) what is the amount of the investment in 5 years?
I got this A=3000(1+0.0175)^10
A=$3568.33
b) How long will it take to double in value?
I am not sure how to do this one
Thanks
Click here to see answer by Edwin McCravy(20059)  |
Question 1168672: The population of a certain species of birds on an island is limited by the type of habitat required for nesting. The population grows according to the function
N(t)=28000/5+13.5e^โ0.038t, where t is measured in years. Find the initial bird population. What is the maximum population that the environment will support? (i.e. as tโโ what does N(t) approach?).According to the model, what will the population be in 10 years? Numeric answer only. Make sure to round your answer correctly.
Click here to see answer by Boreal(15235) |
Question 1168672: The population of a certain species of birds on an island is limited by the type of habitat required for nesting. The population grows according to the function
N(t)=28000/5+13.5e^โ0.038t, where t is measured in years. Find the initial bird population. What is the maximum population that the environment will support? (i.e. as tโโ what does N(t) approach?).According to the model, what will the population be in 10 years? Numeric answer only. Make sure to round your answer correctly.
Click here to see answer by htmentor(1343)  |
Question 1168675: In the early 1960s, radioactive strontium-90 was released during atmospheric testing of nuclear weapons and got into the bones of people alive at the time. If the half-life of strontium-90 is 27 years, what fraction of the strontium-90 absorbed in 1965 remained in people's bones in 1994?
Click here to see answer by Boreal(15235) |
Question 1168676: If possible, solve the equation 1.7(2.8)^(4x)=7(4.6)^x. Give exact answers, not decimals. If there is more than one solution, enter a comma separated list of answers, and enter NONE if there are no solutions.
Click here to see answer by Theo(13342)  |
Question 1169252: The count in a bateria culture was 400 after 10 minutes and 1200 after 30 minutes. Assuming the count grows exponentially,
What was the initial size of the culture?
Find the doubling period.
Find the population after 80 minutes.
When will the population reach 14000.
Click here to see answer by Boreal(15235) |
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