Exercise 9 Page 608

Practice makes perfect

Consider the given table.

Time (Minutes)
9	7	10	12
10	11	8	10
10	17	11	5
9	10	4	12
6	14	8	10

The given table shows the times of 20 presentations. We are asked to display the data in a histogram by using five intervals, beginning with 3-5. To do so, we first need to make a frequency table.

Time (Minutes)	Frequency
3-5	2
6-8	4
9-11	10
12-14	3
15-17	1

We can now display the data in a histogram. To do so, let's set the horizontal axis to be the Time (Minutes) and the vertical axis to be the Frequency. Finally, we will draw bars to represent the frequency of each interval. Let's do it!

b To find which measure of center and variation best represent the data, let's look at the histogram. Since the data on the right of the distribution is approximately a mirror image of the data on the left, the distribution is symmetric. Therefore, the mean and the standard deviation best represent the data.

c Given that the presentations are supposed to be 10 minutes long, we are asked to interpret the data. From the histogram, we can see that most of the data values are around the 9-11 interval. Therefore, most of the presentations are within the required length.

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Exercise 9 Page 608

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