BUSINESS STATISTICS EVALUATION TEST UPDATED
QUESTIONS AND ANSWERS SURE A+
✔✔Given that X is a normal random variable, the probability that a given value of X is
below its mean is ________.
less than 0.5
equal to 0.5
1
greater than 0.5 - ✔✔less than .5
✔✔A random sample is selected so that every element in the population has the same
chance of being included in the sample.
True
False - ✔✔true
✔✔If events A and B are mutually exclusive, then P(A∩B) is always equal to zero.
True
False - ✔✔true
✔✔When the margin of error is added to and subtracted from the sample mean, an
interval is formed that will contain μ with a probability of (1 − α).
True
False - ✔✔True
✔✔If we are testing the difference between the means of two normally distributed
independent populations with samples of n1 = 10, n2 = 10, the degrees of freedom for
the t statistic is ________.
18
20
9
19
8 - ✔✔18
,✔✔If events A and B are independent, then P(A|B) is equal to ________.
P(A∩B)
P(A)
P(B) - ✔✔P(A∩B)
✔✔A regression between foot length (response variable in cm) and height (predictor
variable in inches) for 33 students resulted in the regression equation "FootLength =
10.9 + 0.23(Height)". One student in the sample was 73 inches tall with a feet length of
29 cm. What is the predicted foot length for this student?
17.57 cm
27.69 cm
29 cm
33 cm - ✔✔27.69 cm
✔✔The mean of a standard normal distribution is always equal to ________.
-1
1
0.5
0 - ✔✔0
✔✔An example of a quantitative variable is the manufacturer of a car.
True
False - ✔✔False
✔✔The manager of the quality department for a tire manufacturing company wants to
know the average tensile strength of rubber used in making a certain brand of radial tire.
The population is normally distributed and the population standard deviation is known.
, She uses a z test to test the null hypothesis that the mean tensile strength is 800
pounds per square inch. The calculated z test statistic is a positive value that leads to a
p-value of .045 for the test. If the significance level (α) is .05, the null hypothesis would
be rejected.
True
False - ✔✔True
✔✔In random sampling without replacement, each element in the sample will be
different.
True
False - ✔✔True
✔✔A discrete random variable may assume a countable number of outcome values.
True
False - ✔✔True
✔✔Correlation does not imply __________.
that a relationship exists
dependency
causation
a scatterplot - ✔✔Causation
✔✔The width of a confidence interval will be:
Wider for a sample size of 100 than for a sample size of 50.
Wider when the sample standard deviation (s) is small than when s is large.
Narrower for 99 percent confidence than 95 percent confidence.
Narrower for 90 percent confidence than 95 percent confidence. - ✔✔Narrower for 90
percent confidence than 95 percent confidence
✔✔The z value tells us the number of standard deviations that a value x is from the
mean.
True
False - ✔✔True
QUESTIONS AND ANSWERS SURE A+
✔✔Given that X is a normal random variable, the probability that a given value of X is
below its mean is ________.
less than 0.5
equal to 0.5
1
greater than 0.5 - ✔✔less than .5
✔✔A random sample is selected so that every element in the population has the same
chance of being included in the sample.
True
False - ✔✔true
✔✔If events A and B are mutually exclusive, then P(A∩B) is always equal to zero.
True
False - ✔✔true
✔✔When the margin of error is added to and subtracted from the sample mean, an
interval is formed that will contain μ with a probability of (1 − α).
True
False - ✔✔True
✔✔If we are testing the difference between the means of two normally distributed
independent populations with samples of n1 = 10, n2 = 10, the degrees of freedom for
the t statistic is ________.
18
20
9
19
8 - ✔✔18
,✔✔If events A and B are independent, then P(A|B) is equal to ________.
P(A∩B)
P(A)
P(B) - ✔✔P(A∩B)
✔✔A regression between foot length (response variable in cm) and height (predictor
variable in inches) for 33 students resulted in the regression equation "FootLength =
10.9 + 0.23(Height)". One student in the sample was 73 inches tall with a feet length of
29 cm. What is the predicted foot length for this student?
17.57 cm
27.69 cm
29 cm
33 cm - ✔✔27.69 cm
✔✔The mean of a standard normal distribution is always equal to ________.
-1
1
0.5
0 - ✔✔0
✔✔An example of a quantitative variable is the manufacturer of a car.
True
False - ✔✔False
✔✔The manager of the quality department for a tire manufacturing company wants to
know the average tensile strength of rubber used in making a certain brand of radial tire.
The population is normally distributed and the population standard deviation is known.
, She uses a z test to test the null hypothesis that the mean tensile strength is 800
pounds per square inch. The calculated z test statistic is a positive value that leads to a
p-value of .045 for the test. If the significance level (α) is .05, the null hypothesis would
be rejected.
True
False - ✔✔True
✔✔In random sampling without replacement, each element in the sample will be
different.
True
False - ✔✔True
✔✔A discrete random variable may assume a countable number of outcome values.
True
False - ✔✔True
✔✔Correlation does not imply __________.
that a relationship exists
dependency
causation
a scatterplot - ✔✔Causation
✔✔The width of a confidence interval will be:
Wider for a sample size of 100 than for a sample size of 50.
Wider when the sample standard deviation (s) is small than when s is large.
Narrower for 99 percent confidence than 95 percent confidence.
Narrower for 90 percent confidence than 95 percent confidence. - ✔✔Narrower for 90
percent confidence than 95 percent confidence
✔✔The z value tells us the number of standard deviations that a value x is from the
mean.
True
False - ✔✔True
