# College Algebra

posted by .

20. Growth of an Account If Russ (see Exercise 19) chooses the plan with continuous compounding, how long will it take for his \$60,000 to grow to \$80,000?
3. (1/8) to the 2x-3= 16 to the x +1
13. e to the 4x= 4 to the x-2
15. ln (x-4) ln 3= ln(1/5) to the x power
20. Tripling Time For any amount of money invested at 6.8% annual interest compounded continuously, how long will it take to triple?
Please someone help ASAP!!!!!!!!! I don't understand any of these college algebra problems.

• College Algebra -

19
you want to solve for t
60000 e^.0675t = 80000
e^.0675t = 1.333...
ln both sides and use rules of logs
.0675t lne = ln 1.3333... ( but lne = 1)
t = ln 1.3333../.0675 = 4.26 years, appr 4 years and 3 months

3.
(1/8)^(2x-3) = 16^(x+1)
(2^-3)^(2x-3) = (2^4)^(x+1)
2^(-6x + 9 = 2^(4x + 4)
-6x + 9 = 4x + 4
-10x = -5
x = 1/2

13.
e^(4x) = 4^(x-2)
ln both sides

4x lne = (x-2)ln4
4x = ln4 x - 2ln4
4x - ln4 x = -2ln4
x(4 - ln4) = -2ln4
x = -2ln4/(4-ln4)
= appr -1.0608

15. ln(x-4) ln3 = ln(1/5)^x

no simple algebraic way to solve this, unless I misread the question. I took it the way you typed it
ran it through Wolfram and Wolfram ran out of time trying to solve it

http://www.wolframalpha.com/input/?i=solve++ln%28x-4%29*ln3+%3D+ln%281%2F5%29%5Ex

20. solve

1 e^.068t = 3
now do it the same way as #19

## Similar Questions

1. ### Algebra

If 10,000 is invested at 4.8% simple interest, how long will it take for the account balance to grow to 11,200.
2. ### Algebra

A grandmother is looking for a plan to finance her new grandchild’s college education. She has \$25,000 to invest. Search the internet and locate a long-range investment plan, CD, Savings Bond, etc, for the grandmother. The plan is …
3. ### college algebra

A grandmother is looking for a plan to finance her new grandchild’s college education. She has \$25,000 to invest. Search the internet and locate a long-range investment plan, CD, Savings Bond, etc, for the grandmother. The plan is …
4. ### algebra

At what interest rate would a deposit of \$45,000 grow to \$110,682 in 30 years with continuous 38) compounding?
5. ### math

Assume you want to accumulate \$125,000 for a long-range goal in 40 years. You have two choices. Plan A is an account with annual compounding and an APR of 5%. Plan B is an account with continuous compounding and an APR of 4.5%. How …
6. ### Math

Using continuous compounding. A 13,000 deposit in an account with APR of 4.5 percent is. The balance in the account after 1 year is what.
7. ### Calculous Pre

A population grows from 11,000 to 15,000 in three years. Enter your answers to three decimal places. Assuming the growth is exponential, find the growth rate and continuous growth rate Growth rate ______ %?
8. ### Math

Jasmine invested \$73,000 in a fixed rate account offering 7.2% interest rate compounded semiannually. How long will it take her to grow it to \$100,000?
9. ### Is My Answer Correct Tutors?

You deposit \$9,000 in an account earning 5.5% interest compounded semiannually. How much will you have in the account after 10 years?
10. ### Finite Math

You deposit \$5,000 in an account earning 7.5% interest compounded semiannually. How much will you have in the account after 9 years?

More Similar Questions