  ### Home > MC1 > Chapter 6 > Lesson 6.1.2 > Problem6-18

6-18.

At right is a stem-and-leaf plot showing the weight of each book in Jenna's backpack, measured in ounces. For example, she has a journal that weighs $12$ ounces and a history book that weighs $35$ ounces. After third period, Jenna realized that she had left her science book ($64$ oz) and her paperback novel ($11$ oz) at home. Her mother agreed to bring them to her at lunch.

Think about how the addition of the two books will change the measures of central tendency of the weights of books in her backpack.

For each part below, choose the word or phrase (increase, decrease, or stay the same) that best describes the change and write the complete sentence. For each one, explain how you can tell without calculating.

 $1$ $2\ \ 8$ $2$ $0\ \ 6\ \ 9$ $3$ $5\ \ 5$ $4$ $5$ $6$
1. The mean will ____.

How does the mean of the new books compare to the mean of the original group?

2. The median will ____.

You are adding one number to each end.

3. The mode will ____.

You are not making any numbers appear more often.

4. The range will ____.

Your largest number is changing from $35$ to $64$.

5. Test your predictions by calculating the mean, median, mode, and range before and after the new books are added.

Before: mean $= 25$, median $= 26$, mode $= 35$, range $= 23$.
Remember to calculate the central tendencies after the new books are added.