Basic Mathematics for College Students

584 Chapter 6 Percent

What is 1% of the given number? Find the exact answer and an

estimate using front-end rounding.

61. 342.03 62. 8,687
    What is 10% of the given number? Find the exact answer and an
    estimate using front-end rounding.


62. 43.4 seconds 64. 10,900 liters
    Estimate each answer. (Answers may vary.)


63. What is 20% of 63? 66. What is 20% of 612?


64. What is 50% of 279,985? 68. What is 50% of 327?


65. What is 25% of 13.02? 70. What is 25% of 39.9?


66. What is 5% of 7,150? 72. What is 5% of 19,359?


67. What is 200% of 29.78? 74. What is 200% of 1.125?
    Estimate a 15% tip on each dollar amount. (Answers may vary.)


68. $243.55 76. $46.99

Estimate each answer. (Answers may vary.)

77. SPECIAL OFFERS A home improvement store
    sells a 50-fluid ounce pail of asphalt driveway sealant
    that is labeled “25% free.” How many ounces are
    free?


78. JOB TRAINING 15% of the 785 people attending a
    job training program had a college degree. How
    many people is this?
    Approximate the percent and then estimate each answer.
    (Answers may vary.)


79. SEAT BELTS A state trooper survey on an
    interstate highway found that of the 3,850 cars that
    passed the inspection point, 6% of the drivers were
    not wearing a seat belt. Estimate the number not
    wearing a seat belt.


80. DOWN PAYMENTS Estimate the amount of an
    11% down payment on a house that is selling for
    $279,950.

REVIEW EXERCISES

SECTION 6.5 Interest

Interestis money that is paid for the use of

money.

Simple interestis interest earned on the original

principal and is found using the formula

where Pis the principal,ris the annual (yearly)

interest rate, and tis the length of time in years.

The total amountin an investment account or

the total amount to be repaid on a loan is the sum

of the principal and the interest.

Total amount principal interest

IPrt

DEFINITIONS AND CONCEPTS EXAMPLES

If $4,000 is invested for 3 years at a rate of 7.2%, how much simple

interest is earned?

This is the simple interest formula.

Substitute the values for P, r , and t.

Remember to write the rate ras a decimal.

Multiply: $4,000 0.072 $288.

Do the multiplication.

The simple interest earned in 3 years is $864.

HOME REPAIRS A homeowner borrowed $5,600 for 2 years at

10% simple interest to pay for a new concrete driveway. Find the total

amount due on the loan.

This is the simple interest formula.

Write the rate ras a decimal.

Multiply: $5,600 0.10 $560.

Do the multiplication.

The interest due in 2 years is $1,120. To find the total amount of

money due on the loan, we add.

Do the addition.

At the end of 2 years, the total amount of money due on the loan is

$6,720.

$6,720

 $5,600  $1,120

Total amountprincipalinterest

I$1,120

I$560 2

I$5,6000.10 2

IPrt

P$5,600 r10%0.10 t 2

I$864

I$288 3

I$4,0000.072 3

IPrt

P$4,000 r7.2%0.072 t 3