Basic Mathematics for College Students

403

Dividing a decimal by 0.1, 0.01, 0.001, and so on

To find the quotient of a decimal and 0.1, 0.01,
0.001, and so on, move the decimal point to the
right the same number of decimal places as there
are in the power of 10.

Divide:

Since the divisor 0.001 has three decimal places,

move the decimal point in 1.6402 three places to

the right.

1.6402

0.001

 1,640.2

1.6402

0.001

The rules for dividing integers also hold for
dividing signed decimals. The quotient of two
decimals with like signs is positive, and the
quotient of two decimals with unlike signs is
negative.

Divide: Since the signs of the dividend and divisor

are unlike, the final answer is negative.

Divide: Since the dividend and divisor have like signs,

the quotient is positive.

0.84

4.2

 0.2

1.53  0.3 5.1

We use the order of operations rule to evaluate
expressions and formulas. Evaluate:

In the numerator, evaluate (1.2)^2.

In the denominator, do the addition.

In the numerator, do the subtraction.

Do the division indicated by the fraction

bar.

 90.9



36.36

0.4

37.8  (1.2)^2

0.1  0.3



37.8  1.44

0.4

37.8  (1.2)^2

0.1  0.3

We can use the five-step problem-solving strategy to
solve application problems that involve decimals.

See Examples 10 and 11 that begin on page 366 to review how to

solve application problems by dividing decimals.



REVIEW EXERCISES

Divide. Check the result.

65. 
    
    
    
    66. 
        
    
    
    
    


66. 
    
    
    
    68. 
        
    
    
    
    


67. 
    
    
    
    70. 
        
    
    
    
    


68. 
    
    
    
    72. 
        
    
    
    
    


69. 
    
    
    
    74. 
        
    
    
    
    


70. 
    

    Divide by.

    
    


71. 
    

Estimate each quotient:

77. 
    

78. 
    

Divide and round each result to the specified decimal place.

79. (nearest tenth)


80. (nearest hundredth)


81. Evaluate:


82. Evaluate the formula for .C  F  68.9

5

9

(F  32)

(1.4)^2  2(4.6)

0.5  0.3

5.438

0.007

78.98  6.1

8.825,904.39

4,983.01  41.33

77.021  0.0001

0.8765 0.001

0.0112

 10

89.76  1,000

0.003726

0.0046

15.75

0.25

0.0742

1.4

80.625  12.9

24.618  0.6

29.67

 23

3 27.9 41.8  4

83. THANKSGIVING DINNER The cost of
    purchasing the food for a Thanksgiving dinner for a
    family of 5 was $41.70.What was the cost of the
    dinner per person?


84. DRINKING WATER Water samples from five wells
    were taken and tested for PCBs (polychlorinated
    biphenyls).The number of parts per billion (ppb)
    found in each sample is given below. Find the average
    number of parts per billion for these samples.


85. SERVING SIZE The illustration below shows the
    package labeling on a box of children’s cereal. Use
    the information given to find the number of servings.

Nutrition Facts

Serving size

Servings per container

Package weight

1.1 ounce

?

15.4 ounces

Sample #1: 0.44 ppb

Sample #2:0.50 ppb

Sample #3:0.46 ppb

Sample #4:0.52 ppb

Sample #5:0.63 ppb