Page 187 - NUMINO TG_6A

Activity 1 Solving Proportions

jOb ective Solve problems about proportions.

1. Textbook Instructions Activity 1 Solving Proportions

In this activity, students will use the methods 1 . Solve each proportion.

learned earlier in the unit to solve proportions a 12 a 12
5 30 5 30
that have an unknown variable. Much like = = Cross products

basic algebra, students will find the unknown a 30 = 5 12
30a = 60
variable. Solve the example with students. a=2

Example: Solve a 12 using the cross
5 30

products method.

Multiply a by 30 and 5 by 12. a. 21 a b. 5 b
8 8 12 60
30a 5 12 = =

Simplify. 21 8 = 8 a 5 60 = 12 b
168 = 8a 300 = 12b
30a 60 a = 21 b = 25

Solve for a by dividing 60 by 30.

a 60 , a 2
30
c. 50 = 10 d. 20 = 30
15 c 8 d

1. Have students use cross products to solve 50 c = 15 10 20 d = 8 30 You can take out
the rest of the problems on the page. 50c = 150 20d = 240 the multiplication
c=3 d = 12 symbol between

10 15 28 21 a number and
e 33 44 f variable.

a 30 = 30a

e. = f. =

10 33 = e 15 28 f = 44 21
15e = 330 28f = 924
e = 22 f = 33

102

2. Build Understanding

Though this activity utilizes the basic algebra concept of finding a variable through equations, some

students may struggle with the new presentation of this concept. For students who are having difficulty, use
a
this series of steps, using the example 4 15 .
20

Step 1: Identify what is unknown in the equation. a

Step 2: Use the cross product method to create a basic equation. 20a 4 15

Step 3: Use addition, subtraction or division, what the equation requires, to find the variable.
60
20a 60, a 20 , a 3

170 NUMINO Teacher s Guide