### Savings Account, Mortgage, APR, Excel, Mold Spores, exponential model – Test

The key terms in this Mathematics course include Savings Account, Graph, Mortgage, APR, Excel, Mold Spores, Exponential Model, Substance, Carry Over Balance, Minimum Payment, APR, Finance Charge, Balance.

Use the graph below to calculate the growth factor on the savings account graphed.  Express your answer as a decimal rounded to the nearest thousandth.

1.005 (with margin: 1) – Correct

Your friend is going to borrow \$87,500 using a 15 year mortgage with a 5.25% APR. Which of the following could you type into Excel to find her monthly mortgage payment?

87500 ( .0525 12 ) 12 × 15

= 875000 ( 1 + .0525 12 ) 12 × 15

=FV(0.0525/12,12 x 15,-87500)

0.0525/12 × 15 × 12 × 87500

=PMT(0.0525/12,12 x 15,-87500) – Correct!

=PV(0.0525/12,12 x 15,-87500)

A particular type of mold is growing 9.7% per hour.  Assuming that mold growth continues at this rate and there were 14,000 spores at 12:00am, estimate the expected number of mold spores at 3:30am. (Round your answer to the nearest whole spore. Do not include units on your answer.)

##### 19,358 –Correct

The half-life of a radioactive substance is one day, meaning that every day half of the substance has decayed.  Suppose you have 304 grams of this substance.  Construct an exponential model for the amount of the substance remaining on a given day.  Use your model to determine how much of the substance will be left after 4 days. (Express your answer rounded correctly to the nearest tenth of a gram.  Do not include units with your answer.)

19 (margin of error +/- 2%) – Correct Answer

You carry over a balance of \$400 on a recent purchase of a washing machine, you will just pay the minimum payment each month for the next three months.  The APR is 15.99% and the minimum payment each month is 4% of the balance.  Determine the finance charge, new balance, and minimum payment required for the first month, and the starting balance for month 2 in the table below (round to the nearest cent, do not include units with your answers)