Summer Math Packet Year 8 Page 18
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18Part
12
Whole 16 = 100
Cross multiply
Divide to get n
By itself
So 12 is 75% of 16.
12 x 100 = 16 xn%
1200 =
n
16
75 = n
Level 8 (Pre-Algebra) — Summer Math Packet
Unit: Knowledge of Number Relationships and Computation
Textbook Section: 6-2, 6-3, 6-5
Objective: Solve problems using proportional reasoning
Examples:
•
Proportions are useful in solving a variety of problems.
•
Be sure to set up the proportion according to the labels! Use this to help you set up the proportion.
•
In a PERCENT PROPORTION, one of the numbers, called the PART is being compared to the whole quantity
called the BASE. The other ratio is the %, written as a fraction, whose base is 100.
PERCENT PROPORTION:
%
part
100 = whole
A) Twelve is what % of 16?
C) 225 is 36% of what #?
Part
225
36
Whole
n
100
nx 36 =225x100
36n = 22500
36
36
n =
625
B) What # is 1.4% of 15?
Part
n
1.4
Whole 15 = 100
nx 100 = 15 x 1.4
100n = 21
100
100
n = 0.21
D) If 6 out of 8 students wore shorts to school, how
many students are in the school if there were 630
students wearing shorts?
Part
6
630
Whole 8
n
8 x 630 = 6n
5040 = 6 n
6
6
n = 840 students
1.) Use proportions to solve.
What percent of 60 is 15?
3.) If 5 out of 10 people prefer Trident gum. How many
people out of 20 would you expect to like Trident?
2.) Use proportions to solve.
75 is 20% of what number?
4.) 300 students were surveyed. 50 of them liked
pepperoni pizza the best. How many students would you
expect to like pepperoni pizza if you asked 600 students?
5.) 20% of the M&M's in your bag are the color blue. If
there are 50 M&M's total, how many are blue?
6.) You earned 20 points on a test out of 50. What was
your percent on the test?
Revised 5/09
20
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