Name:_____________________________________per.____
STEPS In Hypothesis Testing – Sec. 8.1
Do you remember ME?  Take out your Chapter 7 NOTES-- Include a picture/bell curve in each problem.
Z-Score for Population
T-Score for Sample
Proportion
or
Chi-Squared
1. 28 employees of XYZ Company travel an average (mean) of 14.3 miles to work. The standard deviation of their travel
time was 2 miles. Find the 95% confidence interval of the true mean or population mean.
Z-Score for Population
T-Score for Sample
Proportion
or
Chi-Squared
2. Find the 95% confidence interval for the standard deviation in the time it takes to fill a car with gas. In a sample of 23
fill-ups, the standard deviation of the time it takes to fill the car is 3.8 minutes. Assume the variable is normally
distributed.
Z-Score for Population
T-Score for Sample
Proportion
or
Chi-Squared
3. A study of 40 English composition professors showed that they spent, on average, 12.6 minutes correcting a student’s
term paper. Find the 90% confidence interval of the mean time for all composition papers when 𝜎 = 2.5
Z-Score for Population
T-Score for Sample
Proportion
or
Chi-Squared
4. A survey found that out of 200 students, 168 said they needed loans or scholarships to pay their tuition and expenses.
Find the 99% confidence interval for the population proportion of students needing loans or scholarships.
Why Hypothesis Testing? What field use it & Why?
Environmental Scientist
Education Trends Analysist
Fashion Design Distributor
Ski Resort
Types of Hypothesis Tests
Methods of Hypothesis Testing
Z-test: 8-2, 8-4
Traditional Method—archaic but utilized since the beginning
T-test: 8-3
P-Value used with statistical calculators and computer packages
Χ2 for variance and
standard deviation: 8-5
Confidence Interval Method
Steps in Hypothesis TESTING
Step 1: State the Hypothesis & Identify the Claim
Example 1: An internet researcher is interested in determining if the time Americans spend on Facebook is
increasing given all the other social media sites. The researcher knows from a recent study the average time
on Facebook is 40 minutes per day.
Which one would be the claim?
Ho : Null Hypothesis
H1 : Alternative Hypothesis
RULES of Hypothesis Statement Creation: Where k is ______________________________________________
Problem #1:
a. The average age of community college
students is 24.6 years. A college consortium
wants to see if average remains the same.
Ho:
H1:
H1:
b. The average age of attorneys is 25.4 years.
A Law firm wants to determine if the age is
increasing as students take longer to
complete school.
Ho:
H1:
c. Will less practice time decrease the
number of average points in a game? he
average score of high school basketball
games, in the past, is 88 points.
Ho:
Step 2: What Type of “Tailed Test” do I use? What is the critical value? Use either TABLE/TI 84 InvNorm
 Draw the Appropriate Figure in Each Situation, showing the critical region
Example 1: a. A left-tailed test with  = 0.10.
Example 3: c. A right-tailed test with  = 0.005
Example 2: b. A two-tailed test with  = 0.02.
HOMEWORK: State the null and alternative hypotheses for each conjecture. Identify the CLAIM.
a. A researcher thinks that if expectant mothers
Ho:
H1:
use vitamin pills, the birth weight of the babies
will increase. The average birth weight of the
population is 8.6 pounds.
b. An engineer hypothesizes that the mean
number of defects can be decreased in a
manufacturing process of I-pads by using robots
instead of humans for certain tasks. The mean
number of I-pads per 1000 is 18.
c. A psychologist feels that playing soft music
during a test will change the results of the test.
The psychologist is not sure whether the grades
will be higher or lower. In the past, the mean of
the scores was 73.
Ho:
H1:
Ho:
H1:
Create the Appropriate Diagram
and Identify the Critical Value..
D.
E.
F.
G.
H.
This study found that people who used pedometers reported having increased
energy, mood improvement, and weight loss. State possible null and alternative
hypotheses for the study.
Ho:
H1:
What would be a likely population?
What is the sample size? Comment on the sample size.