Score 17/22
You passed this Milestone
17 questions were answered correctly.
M
1 I LE S TO N E
5 qu es ti on s w e re a nsw ered incorrectly.
Jean works for the government and was conducting a survey to determine the income levels of a number of different neighborhoods in a
metropolitan area. Based on national data, Jean knows that the mean income level in the country is $40,000, with a standard deviation
of
$2,000. Jean selected three neighborhoods and determined the average income level.
What is the probability that the average income level in the neighborhoods was more than $41,000?
31%
5%
50%
69%
RATIONALE
First we need to find the z-score. The mean is $40,000, the value we are looking for is $41,000, and the standard deviation is $2,000, so
the z-score is:
Next, we need to find this probability in our z-table. A z-score of 0.5 corresponds with a probability of 0.6915. This is actually the
probability that the value is LESS THAN $41,000. So to find the probability that it is greater than $41,000, we need to subtract this
probability from 1:
So the probability that the average income is
greater than $41,000 is about 31%.
,CONCEPT
, Application of z-Scores
I need help with this question
2
As project manager for an online-course design company, Rachel had data that applied to several different course-development
methods. When the company began preparing the next course set, Rachel was interested in how development time varied with each
method.
Determine which graph would have the smallest standard deviation.
You passed this Milestone
17 questions were answered correctly.
M
1 I LE S TO N E
5 qu es ti on s w e re a nsw ered incorrectly.
Jean works for the government and was conducting a survey to determine the income levels of a number of different neighborhoods in a
metropolitan area. Based on national data, Jean knows that the mean income level in the country is $40,000, with a standard deviation
of
$2,000. Jean selected three neighborhoods and determined the average income level.
What is the probability that the average income level in the neighborhoods was more than $41,000?
31%
5%
50%
69%
RATIONALE
First we need to find the z-score. The mean is $40,000, the value we are looking for is $41,000, and the standard deviation is $2,000, so
the z-score is:
Next, we need to find this probability in our z-table. A z-score of 0.5 corresponds with a probability of 0.6915. This is actually the
probability that the value is LESS THAN $41,000. So to find the probability that it is greater than $41,000, we need to subtract this
probability from 1:
So the probability that the average income is
greater than $41,000 is about 31%.
,CONCEPT
, Application of z-Scores
I need help with this question
2
As project manager for an online-course design company, Rachel had data that applied to several different course-development
methods. When the company began preparing the next course set, Rachel was interested in how development time varied with each
method.
Determine which graph would have the smallest standard deviation.
