Population Batch of cookies Sample 10 cookies Variable The number of raisins

1. 9/12/06Warm UpIdentify the population, sample and variableA pastry inspector counts the number of raisins per cookie in 10 oatmeal-raisin cookies in a batch fresh out of the oven.

2. Population • Batch of cookies • Sample • 10 cookies • Variable • The number of raisins • Why would you only inspect a sample and not all of the cookies?

3. The results of 41 students' math tests (with a best possible score of 70) are recorded below: • 31, 49, 19, 62, 50, 24, 45, 23, 51, 32, 48, 55, 60, 40, 35, 54, 26, 57, 37, 43, 65, 50, 55, 18, 53, 41, 50, 34, 67, 56, 44, 4, 54, 57, 39, 52, 45, 35, 51, 63, 42 • Tell me about the data? • Is it well organized?

4. Different types of displays can help organize and make sense of the data. • STEM and LEAF Plots are a quick way to see the distribution (spread) of the data. • Maximum (max) – largest number • Minimum (min) – Smallest number • Range – difference between largest and smallest • Range = Max – Min • Gaps – Holes in the data or no data • Clusters – Large groups of data • Outlier – Values far away from the

5. A teacher asked 10 of her students how many books they had read in the last 12 months. Their answers were as follows: • 12, 23, 19, 6, 10, 7, 15, 25, 21, 12 • Prepare a stem and leaf plot for this data.

6. A good stem and leaf plot • Shows the first digits of the number (thousands, hundreds or tens) as the stem and shows the last digit (ones) as the leaf. • Usually uses whole numbers. Anything that has a decimal point is rounded to the nearest whole number. For example, test results, speeds, heights, weights, etc. • Looks like a bar graph when it is turned on its side. • Shows how the data are spread—that is, highest number, lowest number, most common number and outliers (a number that lies outside the main group of numbers).

7. Dot Plots or Frequency Diagrams