Post on 13-Jan-2016
Averages“Average” when you stop to think of it is a funny concept.
Although it describes all of us it describes none of us. While none of us wants to be the average, we all want to
know about him or her.
1.3 Describing Data
Find an average for each of the following.a) Bo’s test scores
94, 87, 90, 84, 82, 91b) sizes of Nike Air Max sold
9, 9, 9, 12, 11, 8, 6, 9, 9, 10, 7, 6, 9c) cost of homes
125 000, 122 000, 250 000, 120 000, 121 500
The average person is sick in bed seven days a year missing five days of work.
The average man is five feet, nine inches tall; the average woman is five feet 3 inches.
By his or her 70 th birthday, the average person will have eaten 14 steers, 1050 chickens, 3.5 lambs, 25.2 hogs.
• What is an average?
average- a number that describes/represents a set of numbers
– a number that is typical of a set
-averages are also referred to as measures of central tendency
• mean – the sum of the data divided by the number of data values. ex. 11, 9, 7 11+ 9 + 7 = 27 27 / 3 = 9
• median – the middle piece of data - arrange the data in order and find the middle # - if there are an even number of data values, the median is the mean of the middle two ex. a) 2, 4, 5, 6, 10 median = 5 b) 9, 10, 11, 12 10 + 11 = 21 21 / 2 = 10.5
• mode – the number that occurs the most ex. 4, 4, 2, 1, 3, 4, 4, 5 mode = 4 -there can be one, more than one or no mode
Find the mean, median and mode for a – c
a) mean = 88 b) mean = 8.8 c) mean = 147700
median = 88.5 median = 9 median = 122000
mode = n/a mode = 9 mode = n/a
• Suggest which average you feel best describes the data in a – c and/or why one of the averages isn’t good.
• Find the three averages for each of the following situations. Tell which you feel best describes the data and why. a) # of cups of coffee bought 1, 1, 1, 0, 2, 3, 1, 1, 4, 1, 1 b) players weights 201, 204, 208, 105, 210 c) snowfall per day 1.4, 2.6, 4, 7, 3.8, 5.5, 1.8
a) mean = 1.45 b) mean = 185.4 c) mean = 3.7 median = 1 median = 204 median = 3.8 mode = 1 mode = n/a mode = n/a