Basic Mathematics for College Students

564 Chapter 6 Percent

To find the amount of interest $1,010.50 will earn in the second quarter of the

year, we use the simple interest formula, where tis again of a year.

This is the simple interest formula.

Substitute for P, r , and t.

Multiply.

Use a calculator. Round to the nearest cent (hundredth).

The interest earned in the second quarter is $10.61. This becomes part of the

principal for the third quarter.

Add the second-quarter principal and

the interest that it earned to find

the third-quarter principal.

To find the interest $1,021.11 will earn in the third quarter of the year, we proceed

as follows.

This is the simple interest formula.

Substitute for P, r , and t.

Multiply.

Use a calculator. Round to the nearest cent (hundredth).

The interest earned in the third quarter is $10.72. This now becomes part of the

principal for the fourth quarter.

Add the third-quarter principal and

the interest that it earned to find

the fourth-quarter principal.

To find the interest $1,031.83 will earn in the fourth quarter, we again use the

simple interest formula.

This is the simple interest formula.

Substitute for P, r , and t.

Multiply.

Use a calculator. Round to the nearest cent (hundredth).

The interest earned in the fourth quarter is $10.83. Adding this to the existing

principal, we get

Add the fourth-quarter

principal and the interest

that it earned.

The total amount in the account after four quarters, or 1 year, is $1,042.66.

Total amount$1,031.83$10.83$1,042.66

I$10.83

I

$1,031.830.042 1

4

I$1,031.830.042

1

4

IPrt

P4th Qtr$1,031.83 r0.042 t

1

4

Interest earned in the fourth quarter:

P4th Qtr$1,021.11$10.72$1,031.83

I$10.72

I

$1,021.110.042 1

4

I$1,021.110.042

1

4

IPrt

P3rd Qtr$1,021.11 r0.042 t

1

4

Interest earned in the third quarter:

P3rd Qtr$1,010.50$10.61$1,021.11

I$10.61

I

$1,010.500.042 1

4

I$1,010.500.042

1

4

IPrt

P2nd Qtr$1,010.50 r0.042 t

1

4

Interest earned in the second quarter:

14