hours, use the 68-95-99.7 rule to approximate the percentage of light bulbs having a life between 2000 hours
and 3500 hours?
A. About 13.5%
B. About 50%
C. About 68%
D. About 81.5%
Question 6 of 20
5.0/ 5.0 Points
The lifetimes of light bulbs of a particular type are normally distributed with a mean of 270 hours and a
standard deviation of 11 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations
of the mean on either side?
Apply the 68-95-99.7 rule to this questions.
A. 68%
B. 1005
C. 99.7%
D. 95%
Question 7 of 20
0.0/ 5.0 Points

Decide which of the described variables likely have a normal or near-normal distribution.
1. The number of credits remaining until graduation for the students in a small liberal arts college
2. The heights of male students in an advanced placement mathematics class
3. The number of sixes showing when two dice are rolled
A. aB. bC. cD. None
Question 8 of 20
5.0/ 5.0 Points
The annual precipitation for one city is normally distributed with a mean of 28 inches and a standard deviation
of 3.4 inches. Fill in the blanks.
In 95% of the years, the precipitation in this city is between __________ and __________ inches.
Apply the 68-95-99.7 rule to this question.
Question 9 of 20
5.0/ 5.0 Points
The amount of Jen’s monthly electric bill is normally distributed with a mean of $160 and a standard deviation
of $14. Fill in the blanks.95% of her electric bills are between __________ and __________.Apply the 68-95-99.7 rule to this question.

Question 10 of 20
0.0/ 5.0 Points
The systolic blood pressure of 18-year-old women is normally distributed with a mean of 120 mm Hg and a
standard deviation of 12 mm Hg. What percentage of 18-year-old women have a systolic blood pressure that is
within 3 standard deviations of the mean on either side?

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- Spring '19
- Normal Distribution, Standard Deviation, Statistical Analysis