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Math 116 – Chapter 7.2 – CLT Quiz
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Name___________________________
1) For women aged 18-24, systolic blood pressures (in mm Hg) are normally distributed with a mean of 114.8
mm Hg and a standard deviation of 13.1 mm Hg. Describe the shape, the mean and the standard deviation
(standard error) of the distribution of sample means for samples of size 36.
Select the correct choice below:
114.8
a) x-bar is normal with mean =
 19.1 and standard error = 13.1
36
114.8
13.1
b) x-bar is normal with mean =
 19.1 and standard error =
 2.18
36
36
13.1
c) x-bar is normal with mean = 114.8 and standard error =
 2.18
36
d) x-bar is normal with mean = 114.8 and standard error of 13.1
2) The mean annual income for adult men in a certain community is $32,000 and the standard deviation if
$5000. Considering that the distribution of incomes is right skewed,
(a) Determine the distribution of sample means for samples of size 12
 The shape of the x-bar distribution is (circle one)
Approximately normal
Can’t specify with certainty

The mean of the x-bar distribution is_____________________

The standard deviation (standard error) of the x-bar distribution is _______________ (1 decimal place)
(b) Determine the distribution of sample means for samples of size 100

The shape of the x-bar distribution is (circle one)
Approximately normal
Can’t specify with certainty

The mean of the x-bar distribution is_____________________

The standard deviation (standard error) of the x-bar distribution is _______________ (1 decimal place)
3) The times for the mile run of a large group of male college students in a certain college are approximately
Normal with mean 7.11 minutes and standard deviation 0.74 minutes.
a) If we select one male college student at random, what is the probability that his time is more than 8 minutes?
 Graph, label, shade

Use calculator, write calculator input and answer
b) If we select a sample of 16 male-college students at random, what is the probability that their mean time is
more than 8 minutes?
 Graph, label, shade

Use calculator, write calculator input and answer