chapter 3

Question 1

In a normal distribution how do you find the mean?

Answer 1

the number right in the middle of the bell curve

Question 2

The mean of this distribution is

Answer 2

2

Question 3

The distribution of hours of sleep per weeknight among college students is found to be Normally distributed, with a mean of 6.5 hours and a standard deviation of 1 hour. What range contains the middle 95% of hours slept per weeknight by college students?

Answer 3

4.5 and 8.5 hours per weeknight

Question 4

What is the area under a density curve?

Answer 4

exactly 1

Question 5

Where is the median of a density curve?

Answer 5

equal areas point
point that divides the area in half

Question 6

What is the mean of a density curve?

Answer 6

balance point

Question 7

In density curves when are the mean and median equal?

Answer 7

if the distribution is symmetric

Question 8

What is the 68-95-99.7 rule?

Answer 8

*in a normal distribution
68% fall within 1 standard deviations of the mean
95% 2 standard deviations
99.7% 3

Question 9

What is a cumulative population?

Answer 9

for a value x in a distribution is the proportion of observations in the distribution that are less than
or equal to x
(what z-score is finding)