Page 192 - Math Course 3 (Book 2)

Understanding Proportions and Ratios

Using Sampling to Predict
Your Turn!
Example Identify and Describe Samples

To determine the leading candidate for governor,
SPORTS all of the registered voters in one district are called
Miss Newman surveyed every tenth student in the and asked who they favor. Is the sample biased or
hallway to see which sports they preferred watch- unbiased? Describe its type.
ing. 44% preferred football, 28% basketball, 20%
soccer, and 8% tennis. Is this sampling method
valid? If so, out of 560 students in the entire
school, how many would you expect to say they
preferred watching basketball?

This is an unbiased, systematic random sample
since Miss Newman selected students according
to a specific interval. So, this sampling method
is valid. Since 28% of those surveyed preferred
watching basketball, to find how many would say
they preferred watching basketball in the entire
school, find 28% of 560.
A. unbiased; simple random sample
Words What number is 28% of 560? B. unbiased; systematic random sample
C. biased; convenience sample
D. biased; voluntary response sample
Variable Let n = the number of students Answer
preferring to watch basketball.

Equation n = 0.28 × 560
Using Sampling to Predict
n = 0.28 × 560
COLORS To determine favorite colors, students
= 156.8 Multiply. wearing either blue or red were surveyed. 32% pre
ferred blue, 29% preferred red, 23% preferred yellow,
and 16% preferred green. Is this sampling method
Answer Yes; 157 students valid? If so, out of 450 students in the entire school,
how many would you expect to say they prefer red?

MUSIC
A middle school planned to play music during
lunch. Fifty students were randomly surveyed and
asked what type of music they preferred. Sixteen
said they wanted country music. Is this sampling
method valid? If there were 535 students, how
many would you expect to prefer country music?

A. yes; 144 students
B. yes; 29 students
C. yes; 131 students
D. no; invalid sample

Answer

Answer Yes; 171 students

184