Density Curves Review

The 40 yards sprint times for a soccer team are found to be normally distributed with a mean of 5.2 seconds and a standard deviation of 0.3 seconds.  What is the z-score for a player who runs a time of 5.6 seconds?

• -1.33

• 1.33

• 0.88

• 1.02

Between what two standard deviations of a normal distribution contain 68% of the data?

• one below and one above

• two below and two above

• two below and zero

• zero and two above

What is the the total area under the standard normal distribution curve?

• 100

• 25

• .5

• 1

The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a standard deviation of 3 days.

About what percent of the products last between 12 and 15 days?

• 68%

• 34%

• 16%

• 2.5%

A model that describes the overall pattern of a distribution.

• Density Curve

• Approximately Normal

• t distribution

• Chi-Square Distribution

If a density curve is symmetrical, then...

• There is no way to know the relationship between the mean and the median

• The mean should be less than the median

• The mean should be greater than the median

• The mean is generally equal to the median

A class of density curves that are symmetric, single-peaked, and bell-shaped.

• Approximately Normal

• Density Curves

• Histograms

• Unimodel

What percent of a normal distribution lies outside of ±3 standard deviations?

• 99.7%

• .15%

• .3%

• 100%

Which of the following are true?
I) In a normal distribution the mean is always equal to the median
II)All unimodal and symmetric distrubtions are normal for some value of mean and standard deviation
III) In a normal distribution, nearly all of the data is within 3 standard deviations of the mean

• I only

• II only

• III only 

• I and III only

The heights of mature pecan trees are approximately normally distributed with a  mean of 42 feet and a standard deviation of 7.5 feet.  What proportion of pecan trees are between 43 and 46 feet?

• .1501

• .2969

• .4470

• .5530