Basic Mathematics for College Students

366 Chapter 4 Decimals

8 Evaluate formulas.

EXAMPLE 10

Evaluate the formula for and.

StrategyIn the given formula, we will replace the letter Awith 15.36 and h

with 6.4.

WHYThen we can use the order of operations rule to find the value of the

expression on the right side of the symbol.

Solution

This is the given formula.

Replace Awith 15.36 and hwith 6.4.

In the numerator, do the multiplication.

4.8 Do the division indicated by the fraction bar.



30.72

6.4



2(15.36)

6.4

B

2 A

h



b A15.36 h6.4

2 A

h

Self Check 10

Evaluate the formula for

and.

Now TryProblem 63

A5.511 w1.002

lAw

4.8

64 307.2

 256

51 2

51 2

0

1

1

5.3

1

6

 2

30.72

9 Solve application problems by dividing decimals.

Recall that application problems that involve forming equal-sized groups can be

solved by division.

EXAMPLE (^11) French Bread A bread
slicing machine cuts 25-inch-long loaves of French
bread into 0.625-inch-thick slices. How many slices
are there in one loaf?
Analyze

• 25-inch-long loaves of French bread are cut into slices. Given


• Each slice is 0.625-inch thick. Given


• How many slices are there in one loaf? Find
  Form Cutting a loaf of French bread into equally thick slices indicates division. We
  translate the words of the problem to numbers and symbols.

is equal to divided by

 25  0.625

SolveWhen we write in long division form, we see that the divisor is a

decimal.

To write the divisor as a whole number, move the decimal

point three places to the right. To move the decimal point

three places to the right in the dividend, three placeholder

zeros must be inserted (shown in blue).

0.625 25. 000

25 0.625

The number of

slices in a loaf

of French bread

the thickness

of one slice.

the length of

the loaf of

French bread

The number of

slices in a loaf

of French bread

Self Check 11

FRUIT CAKESA 9-inch-long fruit-

cake loaf is cut into 0.25-inch-

thick slices. How many slices are

there in one fruitcake?

Now TryProblem 95