Logarithmic Applications

Steve deposited $5,000 in a savings account that pays 4% interest compounded annually.

Which equation could be used to find the value of the account after 3 years?

• A = 5,000(1 + 4)³

• A = 5,000(1 + 0.04)³

• A = 5,000(1 + 0.4) x 3

• A = 5,000(0.04)³

Given an investment of $1,500:
Which investment would have a larger balance after 5 years?
Option 1 - 4% compounded monthly
Option 2 - 3.9% compounded daily. 

• Option 1
• Option 2

You borrowed $1,690 for 5 1/2 years at an interest of 5.7% compounded annually.  How much extra did you pay by taking out the loan?

• $602.45
• $2,292.45
• $1,87.55
• $3,982.45

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

• 3.0g
• 0.25mg
• 0.3g
• 0.25g

Ms. Reyes deposits $2500 in the bank and earns 5.49% interest monthly. Which equation can be used to determine the amount of money she has after 20 years?

• A(x) = 2500(1 + .0549/12)¹²⁽²⁰⁾

• A(x) = 2500(1 + .0549/12)⁽²⁰⁾

• A(x) = 2500(1 + .0549)⁽²⁰⁾

• A(x) = 2500(1 + .0549)¹²⁽²⁰⁾

If there are initially 2200 bacteria in a culture, and the number of bacteria triple each hour, the number of bacteria after t hours can be found using the formula y = 2200(3)^t . How long will it take the culture to grow to 60,000 bacteria?

• 1.52 hours

• 3.01 hours

• 4.25 hours

• 5.06 hours

Alice would like to buy some new furniture for her home. She decides to buy the furniture on credit with 9.5% interest compounded quarterly. She was able to make a down payment of $7,400. After how many years will she have paid $15,683.28?

• 2 years

• 4 years

• 8 years

• 16 years

You want to save $5,000 for future family vacation. If you assume you can get an interest rate of 4.3% compounded monthly, then how much will you need to invest NOW to reach your vacation goal in 3 years?

• $307,042,791

• $5,000

• $3,250

• $4,395.89

After 15 years Caiden has $839.17 in a savings account. The account paid an interest rate of 3.8% compounded monthly. How much money did Caiden invest originally?

• $800.00

• $475.00

• $495.00

• $774.00

If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

• 1.25mg
• 1.25g
• 10g
• 10mg