An annual marathon covers a route that has a distance of approximately 26 miles. Winning times for this marathon are all over 2 hours. The following data are the minutes over 2 hours for the winning male runners over two periods of 20 years each. Earlier Period 10 8 14 20 16 17 21 21 18 12 18 13 16 24 17 15 15 16 19 6 Recent Period 12 10 8 9 9 9 8 8 8 10 9 9 9 7 7 13 13 8 7 7 (a) Make a stem-and-leaf display for the minutes over 2 hours of the winning times for the earlier period. Use two lines per stem. (b) Make a stem-and-leaf display for the minutes over 2 hours of the winning times for the recent period. Use two lines per stem. (c) Compare the two distributions. How many times under 15 minutes are in each distribution?
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
An annual marathon covers a route that has a distance of approximately 26 miles. Winning times for this marathon are all over 2 hours. The following data are the minutes over 2 hours for the winning male runners over two periods of 20 years each.
Earlier Period
10 8 14 20 16 17 21 21 18 12
18 13 16 24 17 15 15 16 19 6
Recent Period
12 10 8 9 9 9 8 8 8 10
9 9 9 7 7 13 13 8 7 7
(a) Make a stem-and-leaf display for the minutes over 2 hours of the winning times for the earlier period. Use two lines per stem.
(b) Make a stem-and-leaf display for the minutes over 2 hours of the winning times for the recent period. Use two lines per stem.
(c) Compare the two distributions. How many times under 15 minutes are in each distribution?
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