EB Stats Lesson 1 Measures of Center and Spread Name: ________________________ Bk: ___
Math Workshop Mrs. Hofsted
Essential Question: What does the mean and median describe? What does the range describe?
Exploring Data: Caleb and Kim have bowled three games. Their scores are shown in the chart.
Find Caleb’s average score over the three games.
Find Kim’s average score over the three games.
How do Caleb’s and Kim’s average scores compare? Caleb’s game is
scores are
the average.
consistent and his
Suppose they bowl a fourth game, where Caleb scores 150 and Kim scores a 175. How does this affect
their average? Select all that apply.
Reflect: Is the average an accurate representation of Caleb’s bowling? Is the average an accurate
representation of Kim’s bowling. Explain your reasoning.
Mean and median are two commonly used measures of center; they describe a typical value of the
data set. Depending on the data, one measure of center may be more accurate than another in
describing a typical value.
Mean ( ): Sum of the data divided by number of data values (sometimes called average)
Median: Middle value (or average of two middle values) when data is in numerical order
The amount of money Javier earns in tips per day for 6 days is listed below. Find the and median.
$78, $99, $360, $80, $113, $100
Reflect: For the data above, which measure of center, mean or median, is more accurate in describing
a typical amount of money earned?
Range and Interquartile Range are two commonly used measures of spread and they describe the
distribution of data. In other words, they describe how tightly clustered (all numbers close to same
value) or how spread out the values of data set are. The range describes the distribution of the entire
set of data. The interquartile range describes the distribution of the center of the data.
Range:
First quartile ( ):
Second quartile ( ):
Third quartile ( ):
Interquartile range (
):
Largest value in data set minus smallest value in data set.
Median of the lower half of the data set.
Median of the data set.
Median of the upper half of the data set.
Difference between third and first quartiles ( minus ).
The numbers of runs scored by two different softball teams in 15 different games are given below.
Find the range, Q1, median, Q3, and the
for each.