Transcript MS PowerPoint file

There are 6 children in a room, ages
3,4,5,6,7,8. Two more children enter
the room, aged 3 and 8. Then the SD
of the ages of the 8 children will be
___ than the SD of the original 6
children.
A. smaller than
B. larger than
C. the same as
The boxplots show the relationship
between # cylinders a car’s engine
has and the car’s fuel efficiency.
True or false? Cars with a
8-cylinder engine have a
lower median fuel
efficiency than those with a
6-cylinder engine.
A. True
B. False
The boxplots show the relationship
between # cylinders a car’s engine
has and the car’s fuel efficiency.
The IQR of fuel efficiency
of cars with a 4-cylinder
engine is
A. about 5 mpg.
B. greater than 5 mpg.
C. less than 5 mpg.
Suppose the variance of fuel efficiency
of cars with a 4-cylinder engine is 10
mpg2 (mpg = miles per gallon). If we
convert the unit to km per litre (1 mpg
= 0.43 km/litre), then the variance of
fuel efficiency in km/litre will be …
A. 10
C.
B. 10×0.43
D.
10×0.432
100×0.43
The least squares regression line is the
line that makes the sum of the vertical
distances of the data points from the
line as small as possible. True or false?
A.True
B.False
There are 2 midterms in STAT 100. Here are some
summary statistics of the midterm grades:
Midterm 1: SD=5 , Midterm 2: SD=10
Correlation between the scores of the two midterms =
0.80.
Mary is taking STAT 100. Her first midterm grade is 15
points above the mean midterm 1 grade. What will you
predict her midterm 2 grade to be?
A.
B.
C.
D.
24 points above the mean midterm 2 grade.
30 points above the mean midterm 2 grade.
The mean midterm 2 grade.
There is insufficient information to answer the question.
You flip two coins.
Event A = the first flip gives a head
Event B = the second flip gives a tail
The two events are …
A.
B.
C.
D.
E.
complementary.
disjoint.
independent.
both (A) and (C).
both (B) and (C).
Ignoring multiple births, assume babies born
at a hospital are independent with the
probability that a baby is a boy and the
probability that a baby is a girl is both equal
to ½. The probability that the next two babies
born are of the opposite sex is:
1/8
B. 1/6
C. 1/4
D. 1/2
A.
Consider two independent random
variables X and Y. Given that
Var(X)=10 and Var(Y)=4. Then
Var(X – Y) equals to
4
B. 6
C. 10
D. 14
A.
A die is rolled five times. Let X be
the number of 6’s observed. Then:
X is not Binomially distributed.
B. X ~ Bin(6, 1/2)
C. X ~ Bin(6, 1/6)
D. X ~ Bin(5, 1/6)
A.
The lifetime of electric bulbs has mean 440
hours with standard deviation 400 hours.
So the lifetime is not normally distributed.
The sample mean of a simple random
sample of 2 light bulbs:
Will be approximately normally distributed by
the Central Limit Theorem
B. Will be approximately normally distributed by
the Law of Large Numbers
C. Will not be approximately normally
distributed.
A.
The lifetime of electric bulbs has mean 440
hours, with standard deviation 400 hours.
The lifetime is not normally distributed. The
distribution of the lifetimes of a simple
random sample of 100 light bulbs:
Will be approximately normally distributed by
the Central Limit Theorem.
B. Will be approximately normally distributed by
the Law of Large Numbers.
C. Will not be approximately normally distributed.
A.
For a random sample of size 100 of the
bulbs from the previous problem, there
is a 68% chance that the sample mean
is within _____ hours of 440 hours.
4
B. 40
C. 400
A.
The standard deviation of heights of 24-month
old Canadian females is 4 cm. I take a SRS of
100 of these females and find that my sample
mean is 86.1 cm. A 68% confidence interval for
the mean height of all 24-month old Canadian
females:
is 86.1 ± 0.4 cm.
B. is 86.1 ± 4 cm.
C. cannot be calculated as the SRS is biased.
A.
A simple random sample of 100 36-month old
Canadian females yielded a 68% confidence
interval for the mean height of all 36-month
Canadian females: (80.1 cm, 80.9 cm). Then:
68% of all 36-month old Canadian females had heights in
the interval (80.1cm, 80.9cm)
B.
68% of the females in the sample had heights in the
interval (80.1cm, 80.9cm)
C.
There is a 68% chance that the mean height of all 36month old Canadian females is in the interval (80.1cm,
80.9cm).
D.
None of the above.
A.
Suppose that under the null hypothesis,
our test statistics Z has a N(0,1)
distribution, with large values of Z
favouring the alternative hypothesis. We
observe z = 0.2. Then,
The p-value is 0.20
B. The p-value is less than 0.20
C. The null hypothesis is plausible, since z=0.2
is not unusual.
A.
The reading comprehension test scores for fourth graders
are believed to follow the normal distribution. Fifteen
randomly selected fourth graders took the test, and their
scores gave a mean of 73 and an SD of 8. The English
teacher wants to construct a confidence interval for the
mean test score based on the sample of 15 fourth
graders. What distribution will she used to find the critical
point?
The standard normal distribution.
B.
The t-distribution with 14 degrees of freedom.
C.
The t-distribution with 15 degrees of freedom.
D.
None of the above is appropriate as the sample size
15 is not large enough.
A.
Is the mean age of married men greater than the
mean age of married women? You randomly sample
10 married couples. The ages of the 10 husbands
and their wives are recorded. You then carry out a
hypothesis test to answer the above question. Which
of the following hypothesis tests is the most
appropriate?
A.
B.
C.
D.
The paired t-test (1-sided)
The paired t-test (2-sided)
The 2-sample t-test (1-sided)
The 2-sample t-test (2-sided)
In a comparison of gas mileage, measurements were
taken on 10 Honda Civics, 15 Toyota Yaris’ and 30
Mazda 3’s. To test that the mean gas mileages of the
three car types are the same, we would need an F
distribution with numerator degrees of freedom = 2
and denominator degrees of freedom = ?
(ie, the distribution is F2,a , what is our value of a?)
A.
B.
C.
D.
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