Transcript Sooc2205 Midterm Review - University of Western Ontario

Soc2205 Midterm Review
Selected Problems and Solutions
For Midterm
Problem: Healey 1st #2.2 a-e,
2nd #2.2 a-e
• Tips:
– Read questions carefully.
– Answer exactly what is asked.
– Round answers to 2 decimal places.
Solutions to #2.2 a - e
•
•
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•
•
a. 42.36%
b. 0.47
c. 1.41
d. 52.84%
e. 1.12 males for each female
Problems: Healey 1st Can. #3.11, 4.9,
and 2nd Can. #3.11
• For both texts, compute
– the mean,
– the median,
– the range and
– the standard deviation for number of
cars per 100 population
Solutions to 1st Can. #3.11 and 4.9,
2nd Can. #3.11
•
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Mean = 40.25
Median = 44.5
Range = 51 – 10 = 41
Standard deviation = 12.29
Note: Md>Mean indicates a negative skew
Problem: Healey 1st #5.4 a-e,
2nd #4.4 a-e
• Problem Information:
•X
= 50
• s = 10
• Question asks: What % of area….
Example Detailed Solution 5.4a (4.4a)
• For Xi = 40,
• For Xi = 47,
•
•
•
•
•
Xi  X 40  50
Z

 1.00
s
10
Xi  X
47  50
Z

 0.30
s
10
Areas between scores and mean:
For Z = -1.00, Area = .3413
For Z = -0.30, area = .1179
Area between scores: (.3413) - (.1179) = .2234
Solution #5.4 (#4.4) a - e
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•
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a. Percentage = .2234 x 100 = 22.34%
b. 61.79%
c. 61.79%
d. 86.64%
e. 1.39%
Problem: Healey 1st #7.5a,
2nd #6.5a
• Problem Information:
•
•
•
•
 = .10, Z =  1.65
X = 2.3
s = .35
N = 178
Solution to 7.5a (6.5a)

c.i.  X  Z 

s


N 1 
 .35 
c.i.  2.30  1.65 

 177 
 .35 
c.i.  2.30  1.65 

 13.30 (see
 next
page for
c.i.  2.30  1.65(.026) final answer)
Solution to 7.5a (6.5a) cont.
• CI = 2.30 ± .04
• Expand this to:
• “I am 90% confident that the population
average is between 2.26 and 2.34 people
per household”
Problem: Healey 1st #7.9, 2nd #6.9
• Problem Information:
•  = .05,
Z =  1.96
• Ps = (25/178) = . 14
• N = 178
Solution to 1st #7.9, 2nd #6.9
c.i.  Ps  Z
Pu (1  Pu )
N
c.i.  .14  1.96
(.5)(.5)
178
c.i.  .14  1.96
.25
178
c.i.  .14  1.96 .0014
c.i.  .14  (1.96)(.037)
c.i.  .14  .07