Page 223 - NUMINO TG_6A
P. 223
Activity 3 Percents and Proportions
jOb ective Find a value using a proportion.
1. Textbook Instructions Activity 3 Percents and Proportions
Explain to students that when dealing with 1 . Find the value of b using a proportion.
algebraic equations, they can put the variable
at any place in the problem. They can use it to a. 50% of b is 10. b. 25% of b is 20.
figure out the percentage, the original value, or
the end product of the equation. 50 = 10 10 25 = 20 20
100 b 100 b 20
1. Have students solve the problems. Instruct 50 b = 100 25 b = 100
them to write out the equations as before. The
variable is just in a different place. We are now 50 b = 20 100 25 b = 800
solving for the denominator in the proportion
instead of the numerator. c. 20% of b is 13. d. 12% of b is 3.
2. Have students solve the word problems 20 = 13 13 12 = 3 30
using the same method. Have them assign a 100 b 100 b
variable to the number they are asked to find. 20 b = 100 12 b = 100
25 b = 65,0 20 25 b = 250 20
2 . Solve the word problems.
a. 40% of the students in Jessica’s class wear glasses. If there are
30 students who wear glasses, how many students are in Jessica’s class?
total number of students = b, 40 = 30 75 students are in Jessica’s class.
100 b
30
40 b = 100
25 b = 750 20
b. There are 10 students in Ryan’s class. 25% of them play soccer. How
many students are there in Ryan’s class?
total number of students = b, 25 = 10 There are 40 students in Ryan’s class.
100 b
25 b = 100 10
25 b = 400 20
126
2. Build Understanding
Remind students that they are basically using algebra to solve these problems. Terms like “percentages” can
make it sound more confusing that it really is.
Have them remember that various decimals, fractions, and percentages are equivalent with one another. If
they can move between them quickly, they can quickly solve problems. Make sure students are comfortable
expressing numbers in all three forms.
206 NUMINO Teacher s Guide
jOb ective Find a value using a proportion.
1. Textbook Instructions Activity 3 Percents and Proportions
Explain to students that when dealing with 1 . Find the value of b using a proportion.
algebraic equations, they can put the variable
at any place in the problem. They can use it to a. 50% of b is 10. b. 25% of b is 20.
figure out the percentage, the original value, or
the end product of the equation. 50 = 10 10 25 = 20 20
100 b 100 b 20
1. Have students solve the problems. Instruct 50 b = 100 25 b = 100
them to write out the equations as before. The
variable is just in a different place. We are now 50 b = 20 100 25 b = 800
solving for the denominator in the proportion
instead of the numerator. c. 20% of b is 13. d. 12% of b is 3.
2. Have students solve the word problems 20 = 13 13 12 = 3 30
using the same method. Have them assign a 100 b 100 b
variable to the number they are asked to find. 20 b = 100 12 b = 100
25 b = 65,0 20 25 b = 250 20
2 . Solve the word problems.
a. 40% of the students in Jessica’s class wear glasses. If there are
30 students who wear glasses, how many students are in Jessica’s class?
total number of students = b, 40 = 30 75 students are in Jessica’s class.
100 b
30
40 b = 100
25 b = 750 20
b. There are 10 students in Ryan’s class. 25% of them play soccer. How
many students are there in Ryan’s class?
total number of students = b, 25 = 10 There are 40 students in Ryan’s class.
100 b
25 b = 100 10
25 b = 400 20
126
2. Build Understanding
Remind students that they are basically using algebra to solve these problems. Terms like “percentages” can
make it sound more confusing that it really is.
Have them remember that various decimals, fractions, and percentages are equivalent with one another. If
they can move between them quickly, they can quickly solve problems. Make sure students are comfortable
expressing numbers in all three forms.
206 NUMINO Teacher s Guide
