CSUF ISDS 361A Practice Exam 2 Version
B Skordi ACTUAL QUESTIONS AND
CORRECT ANSWERS
-The following 5 questions are based on this information.
Suppose a random sample of 18 uber drivers was taken, and the
average age X¯ of these drivers was found to be 27.5 years. Construct
a 99% confidence interval for the mean age (µ) of all drivers.
Assume that the age of drivers is normally distributed with a
population standard deviation (σ) of 2.3 years. - CORRECT
ANSWERS You need to know this for the next five questions
The standard error (SE) of X¯ is
Select one:
a. 0.13
b. 6.48
c. 2.3
d. 0.54 - CORRECT ANSWERS SE= sigma/sqrt (n)
n 18
mean 27.5
sigma 2.3
d. 0.54
,The critical value (CV) used for a 99% interval estimate is
Select one:
a. 2.58
b. 2.32
c. 0.01
d. 0.005 - CORRECT ANSWERS CV = -
NORM.S.INV(0.01/2)
a. 2.58
The 99% confidence interval estimate of µ is
Select one:
a. 27.5 ± 0.54
b. 27.5 ± 1.26
c. 27.5 ± 2.3
d. 27.5 ± 1.39 - CORRECT ANSWERS Interval Estinate =
Point estimate +/- ME.
ME = CV * SE
PE = 27.5
ME =1.39
d. 27.5 ± 1.39
, The company claims that average age of drivers is 26.9 years. In light
of the sample evidence and at the 1% level of significance,
Select one:
a. Your claim is statistically justified
b. Your claim is not statistically justified - CORRECT ANSWERS
26.5 falls in the range 27.5 +/- 1.39. Hence, the claim is
statistically justified
a. Your claim is statistically justified
If we decrease the confidence level (1-α) from 0.99 to 0.95, the
margin of error (ME) of the confidence interval estimate will
Select one:
a. be zero
b. increase
c. stays the same
d. decrease - CORRECT ANSWERS ME is decreases with
decrease in the confidence level.
d. decrease
The following 6 questions are based on this information.
B Skordi ACTUAL QUESTIONS AND
CORRECT ANSWERS
-The following 5 questions are based on this information.
Suppose a random sample of 18 uber drivers was taken, and the
average age X¯ of these drivers was found to be 27.5 years. Construct
a 99% confidence interval for the mean age (µ) of all drivers.
Assume that the age of drivers is normally distributed with a
population standard deviation (σ) of 2.3 years. - CORRECT
ANSWERS You need to know this for the next five questions
The standard error (SE) of X¯ is
Select one:
a. 0.13
b. 6.48
c. 2.3
d. 0.54 - CORRECT ANSWERS SE= sigma/sqrt (n)
n 18
mean 27.5
sigma 2.3
d. 0.54
,The critical value (CV) used for a 99% interval estimate is
Select one:
a. 2.58
b. 2.32
c. 0.01
d. 0.005 - CORRECT ANSWERS CV = -
NORM.S.INV(0.01/2)
a. 2.58
The 99% confidence interval estimate of µ is
Select one:
a. 27.5 ± 0.54
b. 27.5 ± 1.26
c. 27.5 ± 2.3
d. 27.5 ± 1.39 - CORRECT ANSWERS Interval Estinate =
Point estimate +/- ME.
ME = CV * SE
PE = 27.5
ME =1.39
d. 27.5 ± 1.39
, The company claims that average age of drivers is 26.9 years. In light
of the sample evidence and at the 1% level of significance,
Select one:
a. Your claim is statistically justified
b. Your claim is not statistically justified - CORRECT ANSWERS
26.5 falls in the range 27.5 +/- 1.39. Hence, the claim is
statistically justified
a. Your claim is statistically justified
If we decrease the confidence level (1-α) from 0.99 to 0.95, the
margin of error (ME) of the confidence interval estimate will
Select one:
a. be zero
b. increase
c. stays the same
d. decrease - CORRECT ANSWERS ME is decreases with
decrease in the confidence level.
d. decrease
The following 6 questions are based on this information.
