7th Grade Math

HEALTH Use the table to find the Blood Type Frequencies

ABO Type OABAB

Fraction^ _^1125 _ 5021 _ 101 _ 251

fraction of the total population that

has type A or type B blood.

To find the fraction of the total

population, add _^21

50

and _^1

10

.

_^21

50

+ _^1

10

= _^21 ×^1

50 × 1

+ _^1 ×^5

10 × 5

Rename using the LCD, 50.

= _^21

50

+ _^5

50

Add the fractions.

= _^26

50

Simplify.

= _^13

25

Simplify.

So, _^13

25

of the population has type A or type B blood.

g. SURVEY The graphic shows

the results of an online

survey of over 36,000

youth. How much greater

was the part of youth that

said their favorite way to

be “artsy” was by drawing

than by acting?

Real-World Link

Two to three drops of

blood contain about

one billion red blood

cells.

RR

T

What is your favorite

way to be artsy?

Drawing

Acting

Making music

Taking pictures

Writing

8

25

7

50

7

50

11

100

3

50

Examples 1 and 2 Add or subtract. Write in simplest form.

1. _^4
   9
   
   
   • ^1
     3
     2. - ^5
     6
     
     
     • (- _^4
       9
     
     
     
     
   
   
   
   

(^) ) 3. _^3
8

• (- _^1
  4

(^) ) 4. _^4
5

• ^3
  10
  55 ^1
  6

• _^3
  8

6. _^2
   3

• _^5
  6

7. _^7
   12

• _^5
  6

8. _^3
   4

• _^1
  3

Choose an operation to solve each problem. Explain your reasoning. Then

solve the problem. Write in simplest form.

Example 3

9. MEASUREMENT Cassandra cuts ^5
   16
   inch off the top of a photo and ^3
   8
   inch off
   the bottom. How much shorter is the total height of the photo now?


10. CHORES A bucket was ^7
    8
    full with soapy water. After washing the car, the
    bucket was only ^1
    4
    full. What part of the water was used?

148 Rational Numbers

139_156_C3L2_895130.indd 148 12/31/09 12:37 PM