Ch 11 – Probability & Statistics 11.5 – Measures of Central Tendency and Variation – Day 1

Find the mean, median, and mode of the data. {3, 0, 2, 0, 1, 2, 4} A measure of central tendency is a measure that describes the center of a data set. The mean is the sum of the values in the set divided by the number of values. It is often represented as . (Said “x bar”) The median is the middle value or the mean of the two middle values when the set is ordered numerically. The mode is the value or values that occur most often. Find the mean, median, and mode of the data. {3, 0, 2, 0, 1, 2, 4}

A stem-and-leaf plot is a system used to condense a set of data. The stem is the greatest place value common to all of the data values. The leaf is the smallest place value common to all of the data values. Each row must be arranged in order from least to greatest. Don’t forget to add a key!!! A back-to-back stem-and-leaf plot is used to compare two sets of data.

During Reggie Jackson’s first eight full seasons, he had the following numbers of hits: 128, 151, 101, 157, 132, 158, 146, 150.

A weighted average is a mean calculated by using frequencies of data values. For numerical data, the weighted average of all of the outcomes is called the expected value for the experiment. The probability distribution for an experiment is the function that pairs each outcome with its probability.

The summer movie ratings are given in the table at the right The summer movie ratings are given in the table at the right. Find the weighted average (or expected value) of the ratings for the summer. The probability distribution of successful free throws for a practice set is given below. Find the expected number of successes for one set. Summer Movie Ratings Ratings 4 stars 3 2 1 star # of movies 8 12 7 Weighted average = 8(4) + 12(3)+7(2) +2(1)+1(0) = 2.8 stars 8 +12 + 7 + 2 + 1 # of good free throws, n 1 2 3 Prob. of good free throws 20 5 0* 3 + 1 * 3 + 2 * 1 + 3 * 1 20 20 5 2

A box-and-whisker plot shows the spread of a data set. The quartiles are the medians of the lower and upper halves of the data set. The range is the difference between the highest and lowest data values. The interquartile range is the difference between the 1st and 3rd quartiles.

Make a box-and-whisker plot of the data. Find the interquartile range IQR = 8.5 – 5.5 = 3

Make a box-and-whisker plot of the data. {5, 3, 9, 2, 14, 6, 8, 9, 5, 8, 13, 3, 15, 7, 4, 2, 12, 8}