a.)
State the random variable.
X random variable is Cholesterol level
b.)
Find the probability that a woman age 45-59 in Ghana has a cholesterol level above 6.2
mmol/l (considered a high level).
0.136
c.)
Suppose doctors decide to test the woman’s cholesterol level again and average the two
values.
Find the probability that this woman’s mean cholesterol level for the two tests is
above 6.2 mmol/l.
0.06
d.)
Suppose doctors being very conservative decide to test the woman’s cholesterol level a third
time and average the three values.
Find the probability that this woman’s mean cholesterol
level for the three tests is above 6.2 mmol/l.
0.028
e.)
If the sample mean cholesterol level for this woman after three tests is above 6.2 mmol/l,
what could you conclude?
If this was the case, it could not be unusual for the women to have 2 out of 3 mean
cholesterol levels above 6.2 mmol/l, but could be unusual for them to have all 3 mean
cholesterol levels above 6.2 mmol/l.
6.5.8
A dishwasher has a mean life of 12 years with an estimated standard deviation of 1.25 years ("Appliance
life expectancy," 2013).
The life of a dishwasher is normally distributed.
Suppose you are a
manufacturer and you take a sample of 10 dishwashers that you made.
a.)
State the random variable.
Random variable is the dishwasher
b.)
Find the mean of the sample mean.
12
c.)
Find the standard deviation of the sample mean.
0.395
d.)
What is the shape of the sampling distribution of the sample mean?
Why?
Symmetrical because the life of the dishwasher is normally distributed.

e.)
Find the probability that the sample mean of the dishwashers is less than 6 years.
NADA
f.)
If you found the sample mean life of the 10 dishwashers to be less than 6 years, would you
think that you have a problem with the manufacturing process?
Why or why not?
Probably, because the probability of the sample mean of the dishwashers life being <6
years is NADA (0%).

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