1. Lesson 27 Mean, Median, and Mode

2. Different techniques can be used to understand a set of data. One common way is to use the mean or average. Another is the median, which is the middle number, and the third is the mode, which is the most frequent number in a set of data.

3. Example 1 Marla took a survey of movie prices at ten movie theaters and found these results. What is the mean or average price?

4. Strategy: Use the definition of mean. Step 1: Compute the mean by finding the sum of the prices and dividing it by the number of prices. Sum = 1 x 4.50 + 2 x 5.00 + 1 x 5.50 + 5 x 6.00 + 1 x 7.00 = 57 57/10 = 5.7

5. Solution The mean price is $5.70.

6. Example 2 Find the median of the prices in Example 1. Strategy: Use the definition of median. Step 1: List the prices in rank order. 4.50, 5.00, 5.00, 5.50, 6.00, 6.00, 6.00, 6.00, 6.00, 7.00.

7. Step 2: Find the median for an even number of items. Since there are 10 prices, find the average of the two middle prices – the fifth and sixth. (6.00 + 6.00)/2 = 6.00 (median price).

8. Solution The median price is $6.00.

9. Example 3 Find the mode of the prices listed in Example 1. Strategy: Use the definition of mode. Step 1: The mode is the most frequent number.

10. Solution The mode is $6.00.

11. A set of numbers may have more than one mode, or no mode at all, but they will always have a median and a mean.