STAT 200 Week 6 Homework Problems
Rubric
Correct Answers with no work shown or partial work shown to justify the answer is graded
at 50%.
1.
Many high school students take the AP tests in different subject areas
...
STAT 200 Week 6 Homework Problems
Rubric
Correct Answers with no work shown or partial work shown to justify the answer is graded
at 50%.
1.
Many high school students take the AP tests in different subject areas. In 2007, of the 144,796
students who took the biology exam 84,000 of them were female. In that same year, of the
211,693 students who took the calculus AB exam 102,598 of them were female ("AP exam
scores," 2013). Estimate the difference in the proportion of female students taking the biology
exam and female students taking the calculus AB exam using a 99% confidence level.
Answer:
P
1=84000/144796=0.5815
P
2=102598/211693=0.4846
n1 =144796, n2=211693
99% confidence interval for difference in p1-p2
=(0.5815-0.4846)+/-1.645*sqrt((0.5815*(1-0.5815)/144796)+(0.4846*(1-0.4846)/211693))
=0.0968+/-0.0028
=(0.0941, 0.0996)
2.
Are there more children diagnosed with Autism Spectrum Disorder (ASD) in states that have
larger urban areas over states that are mostly rural? In the state of Pennsylvania, a fairly urban
state, there are 245 eight year olds diagnosed with ASD out of 18,440 eight year olds evaluated.
In the state of Utah, a fairly rural state, there are 45 eight year olds diagnosed with ASD out of
2,123 eight year olds evaluated ("Autism and developmental," 2008). Is there enough evidence
to show that the proportion of children diagnosed with ASD in Pennsylvania is more than the
proportion in Utah? Test at the 1% level.
Answer:
n1=18,440
x1=245
p1=245/18440 = 0.013
q1=1-0.013 = 0.987
n2=2,123
x2=45
p2=45/2123 = 0.021
q1=1-0.021 = 0.979
p-= (245+45)/(18440+2123) = 0.014
q-=1-0.014 = 0.986
z={(0.013+0.021)-0}/sqrt[{(0.014*0.986)/18440}+{(0.014*0.986)/2123}]
z=12.760
3.
All Fresh Seafood is a wholesale fish company based on the east coast of the U.S. Catalina
Offshore Products is a wholesale fish company based on the west coast of the U.S. Table #9.2.5
contains prices from both companies for specific fish types ("Seafood online," 2013) ("Buy sushi
grade," 2013). Do the data provide enough evidence to show that a west coast fish wholesaler is
more expensive than an east coast wholesaler? Test at the 5% level.
Table #9.2.5: Wholesale Prices of Fish in Dollars
Fish
All Fresh
Seafood
Prices
Catalina
Offshore
Products Prices
Cod 19.99 17.99
Tilapi 6.00 13.99
Farmed Salmon 19.99 22.99
Organic Salmon 24.99 24.99
Grouper Fillet 29.99 19.99
Tuna 28.99 31.99
Swordfish 23.99 23.99
Sea Bass 32.99 23.99
Striped Bass 29.99 14.99
Answer
X = 216.92 / 9 = 24.10 Y = 194.91 / 9 = 21.66
S1 = 534.3 / 8 = 66 .82 S2 = 250.00 / 8 = 31.25
T = 924.10- 21.66) / √ ((66.82 / 8 ) – 31.25 / 8)) = 2.44/2.11 = 1.16
Test Statistic: t = 2.45 / (7.39/√9) = 0.995
P value: 0.825
P value is less than test statistic
There is enough evidence to conclude that West Coast wholesale is more expensive then the
East Coast
4.
The British Department of Transportation studied to see if people avoid driving on Friday the
13th. They did a traffic count on a Friday and then again on a Friday the 13th at the same two
locations ("Friday the 13th," 2013). The data for each location on the two different dates is in
table #9.2.6. Estimate the mean difference in traffic count between the 6th and the 13th using a
90% level.
Table #9.2.6: Traffic Count
Dates 6th 13th
1990, July 139246 138548
1990, July 134012 132908
1991, September 137055 136018
1991, September 133732 131843
1991, December 123552 121641
1991, December 121139 118723
1992, March 128293 125532
1992, March 124631 120249
1992, November 124609 122770
1992, November 117584 117263
Answer:
Mean= 1835.8
Standard Dev= 1173.065
df= 9
tc= 1.833
E= 679.962
There is a 90% chance that 2515.762
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