2. Survey Questions
O Q1 - What grade are you in?
O Q2 - How old are you?
O Q3 - Are you male or female?
O Q4 - How many siblings do you have?
O Q5 - How many people live in your house?
O Q6 - How many days of the week do you
typically get homework?
O Q7 - How many pairs of jeans do you own?
3. Questions continued ….
O Q8 - Which do you prefer to watch: College
Football or Professional Football
O Q9 - What type of phone do you prefer: Touch
screen or Full Keyboard
O Q10 - Which do you prefer: Fast Food or
Home-made Food
O Q11 - Would you rather play videogames or
physical sports?
4. Confidence Intervals for Means
Question 1: Grade level of participants
x= 9.93 s= 1.095 n= 84 df= 83
9.93 ± (T*)×(1.095/√84)
= (9.70, 10.16)
O This confidence interval means that we
are 95% confident that the true mean
grade level of survey participants is
between 9.70 and 10.16
5. Confidence Intervals for Means
Question 2: Age of participants
x= 15.27 s= 1.19 n= 84 df= 83
15.27 ± (T*)×(1.19/√84)
= (15.02, 15.53)
O This confidence interval means that we
are 95% confident that the true mean age
of survey participants is between 15.02
and 15.53
6. Confidence Intervals for Means
Question 4: Number of siblings participants
have
x= 2.63 s= 1.63 n= 84 df= 83
2.63 ± (T*)×(1.63/√84)
= (2.28, 2.98)
O This confidence interval means that we
are 95% confident that the true mean of
number siblings of survey participants is
between 2.28 and 2.98
7. Confidence Intervals for Means
Question 5: Number of people in
participant’s household
x= 5.71 s= 2.39 n= 84 df= 83
5.71 ± (T*)×(2.39/√84)
= (5.20, 6.23)
O This confidence interval means that we
are 95% confident that the true mean of
people in the household of survey
participants is between 5.20 and 6.23
8. Confidence Intervals for Means
Question 6: Day of week participants typically
receive homework
x= 4.44 s= 1.13 n= 73 df= 72
4.44 ± (T*)×(1.13/√73)
= (4.17, 4.70)
O This confidence interval means that we are
95% confident that the true mean of days
per week survey participants receive
homework is between
9. Confidence Intervals for Means
Question 7: Pairs of jeans participants own
x= 10.91 s= 12.87 n= 67 df= 66
10.91 ± (T*)×(12.87/√67)
= (7.77, 14.05)
O This confidence interval means that we
are 95% confident that the true mean age
of survey participants is between 7.77 and
14.05
10. Confidence Intervals for
Proportions
Question 3: Gender (p=female q=male)
p= .548 q= .452 z*= 1.960 n= 84
.548 ± 1.960√((.548×.452)/84)
= (.442, .654)
O This means that we are 95% confident
that the true proportion of affirmative
participants (females) is between .442 and
.654
11. Confidence Intervals for
Proportions
Question 8: Watching NFL vs. NCAA Football
(p = prefer NFL ; q = prefer NCAA)
p= .868 q= .132 z*= 1.960 n= 76
.868 ± 1.960√((.868×.132)/76)
= (.792, .944)
O This means that we are 95% confident that
the true proportion of affirmative participants
(prefer watching NFL) is between .792 and
.944
12. Confidence Intervals for
Proportions
Question 9: Touch screen vs. Full Keyboard
(p= Full keyboard q= Touch screen)
p= .561 q= .439 Z*= 1.960 n= 82
.561 ± 1.960√((.561×.439)/82)
= (.454, .668)
O This means that we are 95% confident
that the true proportion of affirmative
participants (prefer a full keyboard cell
phone) is between .454 and .668
13. Confidence Intervals for
Proportions
Question 10: Fast food vs. Home-made
(p= Fast Food q= Home-made)
p= .296 q= .701 Z*= 1.960 n= 81
.296 ± 1.960√((.296×.701)/81)
= (.197, .396)
O This means that we are 95% confident that
the true proportion of affirmative
participants (prefer fast food) is between
.197 and .396
14. Confidence Intervals for
Proportions
Question 11: Videogames vs. Physical
sports
(p= Videogames q= Sports)
p= .266 q= .742 Z*= 1.960 n= 79
.266 ± 1.960√((.266×.742)/79)
= (.168, .364)
O This means that we are 95% confident that
the true proportion of affirmative
participants (prefer playing videogames) is
between .168 and .364
15. Hypothesis Test: Question 6
How many days of the week do you typically get
homework?
“ … researchers say that American students have just the right amount of
homework.”
1. Ho: x=4.44 Ha: x≠4.44
2. Assumptions/Conditions:
*Randomness-our sample was randomly selected
*10%-our sample is less than 10% of the student population
*Distribution-we can assume that the sample is randomly
distributed
3. We will conduct a 1 sample T-test
4. p-value= .612
5. With such a high p-value we cannot reject the null hypothesis.
This means that we can assume that the average student receives
homework about four to five days a week.
16. Larger Study Links
O Question 6-
http://www.greatschools.org/students/homework-
help/251-homework-is-too-much.gs
O Question 7-
http://www.fashionwindows.net/2009/06/american-
own-7-pairs-of-denim-jeans-on-average/
O Question 8-
http://www.cbssports.com/collegefootball/story/112
12751
17. Males vs. Females: Question 11
Would you rather play videogames or physical
sports?
1. Ho: proportion of males > proportion of females (prefer
playing video games)
Ha: proportion of males < proportion of females (prefer
playing video games)
2. Assumptions/Conditions:
*Randomness-our sample was randomly selected
*10%-our sample is less than 10% of the student
population
*Distribution-we can assume that the sample is
randomly distributed
3. We will conduct a 2-proportion Z-test
4. females = .256 males = .286
p-value = .322
5. With a high p-value we cannot reject the null hypothesis.
This means that we can assume that the average teenage
male prefers to play video games over physical sports than the
average teenage female.
