STUDY GUIDE for INFERENCE ABOUT MEANS QUIZ
Answers
1. Parking
a) You should know the conditions that must be met and how to explain/show that those are conditions are met to justify use of the t-model.
b) (122.2,129.8)
c) You should be able to explain in context what the confidence interval means.
d) You should be able to explain in context what 90% confidence interval means.
e) What is your conclusion?
2. Marriage
a) H0: The mean age at which American men firsts marry is 23.3 years old. u=23.3
HA: The mean age at which American men first marry is greater than 23.3 years. u>23.3
b) You should be able to explain if the conditions are satisfied.
c) A description of the sampling distribution would include the degrees of freedom, the mean, and the standard deviation. You should be able to explain in context what the confidence interval means.
d) t=1.07, P-value = 0.1447
e) You should be able to explain what the P-value means
f) You should be able to state your conclusion.
3. Pulse Rates
a) You should be able to interpret the box plot in terms of mean pulse rates and variability. This topic was covered in the first ½ of the year.
b) You would be able to determine if the conditions are satisfied for using the t-test.
c) (-3.025, 3.275) Explain what this confidence means in context.
d) Since 0 is in the interval, there is no evidence of a difference.
4. Tees
Treat this Two Independent Sample problem as a 4-step hypothesis testing problem.
Step 1
H0: Set up a statement where the two means are equal.
HA Set up a statement where the Stinger mean is greater than the Regular mean.
Step 2
Demonstrate that the conditions are satisfied.
Step 3
Do the math. Use a 2-sample t-Test.
df=7.03
SE = 0.4000
Difference between mean velocities: 1.83
P-value = 0.0013
Step 4
Conclusion—state your conclusion
5. Summer School
Treat this Paired Sample problem as a 4-step hypothesis testing problem.
Step 1:
H0: Create a hypothesis statement here. (difference between means is zero)
HA: Create a hypothesis statement here. (difference between means is > 0)
Step 2
Demonstrate that the conditions are satisfied.
Step 3
Do the math. Use a 1-sample t-Test using the differences between the June and August as the one sample.
df=5
mean of differences is 5.3333
mean of H0 is 0
SE = 7.44759/sqrt(6)
t=1.75
P-value =0.0699
Step 4
Conclusion—state your conclusion
6. Sleep
This is a Paired Sample problem.
a) H0: Create a hypothesis statement here. (difference between means is zero)
HA: Create a hypothesis statement here. (difference between means is > 0)
b) P-value = 0.0035
c) You should be able to interpret this result
d) You should be able to state your conclusion.
e) In your conclusion, did you “fail to reject” or “reject” the null hypothesis? If you failed to reject, then what type of error could you have made? If you rejected the null hypothesis, what type of error could you have made?