1) Z=(9.98-10)/(0.03/sqrt(3) = -1.15
2) (16.5-25.7)+-2.39*sqrt(41.785/36+41.785/36) = ( -12.84, -5.56)
3) Cannot do not normal
4)
DF
SS
MS
Groups
2
8.6402
4.321
Error
9
1.6128
1792
Total
11
10.253
5) .02/2=1.282*sqrt(.3(1-.3)/n)
N=3451.4
Need 3452 emails
F
24.108
6)
H0: Hair color and eye color are independent
Ha: Hair color and eye color are dependent
Exp
Brown
Blue
Green
2
Hours
5
Hours
7
Hours
22.1
19.1
17.7
24
20.8
19.2
28.8
25.0
23.1
χ24 = 7.412
Partial Brown
Chi^2
2
0.37
Hours
5
1.042
Hours
7
2.15
Hours
Blue
Green
0.07
0.16
1.62
0.03
1.94
0.03
.1 < P-value < .15
Therefore Fail to Reject the null
Which means there is not sufficient evidence to prove that beam color and fire resistance are
dependent
7) 0.02<p-value<0.04
8)
H0: proportions are equal (not cheating)
Ha: proportions are not equal (is cheating)
Alpha = 0.05
18 20
18 14


32 50
38 44
z

 1.439
38  38  38  38 
32  32  32  32 
1  
1  
1  
1  
82  82  82  82 
82  82  82  82 


32
50
38
44
18
20
14.83 23.17
0.678 0.434
14
30
17.17 23.83
0.5852 0.3747
X21=2.072
p-value = 0.0749
0.10<p-value<0.15
Fail to Reject
We cannot say my daughter is cheating
9) (14-15) +- 2.998*1.22/sqrt(8) = (-2.29, 0.293)
10)
H0: B1=0
Ha: B1≠0
α=0.05
t5=-1.02/0.246 = -4.15
2*.0025<p-value<2*0.005
0.005<p-value<0.01
Reject
Heavier cars do not carry the same amount of Freon
11)
H0: mu >=2
Ha: mu < 2
Type 1 error: The batteries will last, but we think they will die (lose money)
Type 2 error: The batteries will not last, but we think they will (no calculator during test)
Personally I would raise alpha, maybe 0.20 because I don’t want my calculator to die during the
exam, and this would make it more likely that I am going to replace them (even if I don’t need
to)
12)
______ 95% of the time confidence intervals like this capture the true average time between a felony
______ We are 95% confident the true average is between 2.3 and 5.7 seconds
13)
H0:μ≤1
Ha:μ>1
α=0.05
Note that “Error” refers to how far off from 2
1.9  1.02  1.98  2.46
x
 1.84
4
s
t3 
1.9  1.842  1.02  1.842  1.98  1.842  2.46  1.842
4 1
 0.6
1.84  1
 2.8
0.6
4
0.025<p-value<0.05
Reject the null
The average error from the scale is significantly more than 1, which means the scale needs to be
replaced
14)
9 said do the homework
7 said enjoy the songs
5 said take good notes
4 said study with classmates
4 said don’t use the book
3 said attend class
2 said go back over the homework
2 said get help when you need it
2 said start the homework early
Other responses:
Put confidence intervals on your study sheet
Learn the language of statistics
Pay attention to the wording and context of the questions
Make a flow chart
Go to office hours
Make a good study sheet for the exam
Study hard
Pay attention in class
It’s not that hard
Do the practice exams
Don’t do the homework all on one day
Don’t work 30 hours and take 15 credits
Use engineering paper
Beware the final!
Don’t forget everything on the final
Everyone hates statistics. Just do better than the next guy and get it over with
You’ll never get an A in this class
Run! The instructor is insane and possibly dangerous. Quit this silliness and join the college of business
Dr. Crawford is a thug and he don’t take no crap. Don’t give him crap.
Good luck roll Tide
Statistics is like a garden. Dig it