STA 2023 Practice Test 3
For all problems, round calculated values to the same
number of places as the critical value from the table.
For confidence intervals, answers should be in algebraic
“between” form.
Make sure you designate whether the claim is Ho
or Ha !!
1) (9 points) For the population of
male college students, m = 69.0 inches. A random sample of 50 male students had 
= 69.6 inches and 
= 3.0 inches. Test the
claim that the mean is 69 with a = .05.
DRAW IT!! Ho :
Ha :
One-tail or two-tail?
Test screen
Critical
value
Calculated
value
Decision (Reject Ho or Fail to reject Ho?)
Conclusion
statement:
2) (4 points) Find the 90% confidence interval for the population mean for #1. (round values to the nearest tenth).
Screen:
Conf.
Int.
3) (10 points) Sample statistics for 
= 24 are = 2.35 and = 0.7. With a =
.05, test the claim that the mean GPA is greater than 2.0.
DRAW
IT!! Ho :
Ha :
One-tail or two-tail?
Degrees
of freedom:
Critical
value:
Screen:
Calculated
value:
Decision:
Conclusion statement:
4) (4 points) Find the 90% confidence interval for the population mean for #3 (to the nearest thousandth.)
Screen
Conf.
Int.
5) (9 points) OMIT THIS QUESTION
Math majors: 
= 75, 
= 15
English majors: 
= 60, 
= 70, 
= 14
6) (4 points) Find the 90% confidence interval for the difference between the means for #5. ( round to the tenths place.)
Screen:
Conf.
Int.:
7) (9 points) OMIT THIS QUESTION
Faculty 
Students 
8)(4 points) Find the 98% confidence interval for the difference between the population proportions for #7 (round to the hundredths place)
Screen:
Conf. Int.
9) (11 points) Women:
= 25, 
= 75.7, 
=16.8
Men:
= 16, 
=107 
=12.4
OMIT THIS QUESTION
11) (4 points) Find the 98% confidence interval for the difference between the population
means (round values to the nearest hundredth).
Screen
C.I.
14) In 1990, 5.8% of job applicants failed the drug test. At the 0.02 significance level,test the claim that the failure rate is now lower if a random sample of 1520 current job applicants results in 58 failures.
Ho :__________________________
DRAW
IT!!
Ha :__________________________
One-tail or two-tail?_____________
Critical value:__________________
Calculated value: _______________
Reject Ho or Fail to reject Ho ?
_____________________________
Conclusion statement: _____________________________________________________
15) A survey of 400 students at a college found that 7% carry a gun, knife, or other such weapon. Use a = .05 to test the claim that 9% of all college students carry such weapons.
Ho :__________________________
Draw
it!!
Ha :__________________________
One-tail or two-tail?_____________
Critical value: _________________
Calculated value :______________
Reject Ho or Fail to reject Ho ?
_____________________________
Conclusion Statement:_____________________________________________________
16) A random sample of 1200 households with TV sets in use shows 264 were tuned to “60 Minutes”. Test the claim that more than 20% of viewers watch “60 Minutes” with a=.05.
Ho :_________________________
Draw
it!!
Ha :_________________________
One-tail or two-tail?____________
Critical value; _________________
Calculated value :______________
Reject Ho or Fail to reject Ho ?
____________________________
Conclusion Statement: ____________________________________________________
For # 17 – 18, use the appropriate formula & show your plug-ins to find the margin of error and the confidence interval. (Write your interval as an algebraic “between” expression.)
17) Times between uses of a TV remote control by males during commercials:
= 7.6 sec.; = 2.72 sec. ; = 150 ; 98% confidence interval (round to the nearest
hundredth.)
M.E. =________________________
C.I. __________________________
18) IQ scores of professional
athletes: 
= 12;
25; 99% confidence
interval (round to the tenths place.)
M.E.= _______________________
C.I.__________________________
For #19 – 21, use the appropriate calculator screen to find the confidence interval. Write your answer as an algebraic “between” expression.
19) Starting salaries of college graduates who have taken a Statistics course:
= $43,704;
= $9879; 100; 95% confidence interval (to the nearest dollar).
screen _______________________
C.I.__________________________
20) In a random sample of 1200, 800 answered “yes”. 90% confidence interval for the population proportion (round to thousandths place.)
screen _______________________
C.I.__________________________
21) 98%
confidence interval for 
, 
, and 
for a Statistics test.
(round to tenths place).
Screen_______________________
C.I._________________________