Statistics Outliers and Standard Deviation

If we use the median to measure the typical value or center of the data, we would use the _________ to measure the variability.

• Mode

• MAD

• Standard Deviation

• IQR or Interquartile Range

What does the standard deviation tell us about the data set?

• How spread out the numbers are

• How much each number in the data set increases by

• How much each number in the data set decreases by

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 9 and 18 days?

• 68%

• 34%

• 81.5%

• 13.5%

The z-score represents.....

• the amount of standard deviations a data value is above or below the mean.

• the percentile the data value is above or below the mean.

• the amount of standard deviations a data value is above or below the median.

• the percent the data value is above or below the mean.

Fernando is 60 inches tall. The average height for his age and gender is 68 with a standard deviation of 10 inches. If the average height of males is normally distributed, what percent of his peers are shorter than him?

• 46.81%

• 8%

• 78.81%

• 21.19%

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

95% of test scores are between 74 and 92. Assuming this data is normally distributed, choose the correct mean and standard deviation.

• mean: 83

• mean: 85

• standard deviation: 9

• standard deviation: 4.5

A company makes parts for a machine. The lengths of the parts must be within certain limits or they will be rejected. A large number of parts were measured and the mean and standard deviation were calculated as 3.1 m and 0.005 m respectively. Assuming this data is normally distributed and 99.7% of the parts were accepted, what are the limits?

• Between 3.075 m and 3.125 m

• Between 3.080 m and 3.120 m

• Between 3.085 m and 3.115 m

• Between 3.090 m and 3.110 m

Which of the following sets of data is likely to have the smallest standard deviation?

• 1, 2, 4, 6, 9, 12

• 3, 3, 3, 4, 4, 5

• 0, 5, 8, 12, 15, 22

• not enough information

The number of text messages sent per day are as follows:

148, 148, 110, 84, 101, 122, 100, 90, 110, 118, 60, 104, 198, 142

Find the reasonable range and determine if there are any outliers.

• 79 - 164; outliers: 60, 198

• 58 - 188; outlier: 198

• 37 - 205 ; no outliers

• 62 - 200: outliers: 60