Answer:
- median: 15
- mode: 15
- mean: 16
Explanation:
There are 40 numbers in your data set. (This is the sum of the numbers in the Frequency column.) This is an even number, so the median is the average of the middle two Speed values when they are sorted from lowest to highest. The frequency chart already tells you the result of that sorting. From the chart, we can see that there are 9 Speed values below 15, and 12 values that are 15. That tells us that Speed values number 20 and 21 on the list both have a value of 15, so that is the value of the median.
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The mode is the value that occurs most frequently. Obviously that value is 15, since it occurs 12 times and no other number occurs more than 6 times.
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Finding the mean is a little more work. For that, we have to add up the 40 numbers and divide by 40. The fact that some numbers are repeated can help shorten that effort.
sum of all values = 12×1 + 13×2 + 14×6 + 15×12 + 16×6 + 17×5 + 18×1 + 19×2 + 20×4 + 21×1 = 640
mean = (sum of all values)/(number of values) = 640/40
mean = 16