## 500 Marbles

## Opening

# 500 Marbles

The glass jar contains 500 yellow, blue, red, and green marbles.

How many marbles of each color do you think there are in the jar? Record your guesses.

- Yellow
**__** - Blue
**__** - Red
**__** - Green
**__**

The glass jar contains 500 yellow, blue, red, and green marbles.

How many marbles of each color do you think there are in the jar? Record your guesses.

- Yellow
**__** - Blue
**__** - Red
**__** - Green
**__**

Determine the number of each color marble in a jar by analyzing samples, and explore the effect of sample size.

You will take samples from the jar as specified below. The Marble Jar interactive will create samples that represents the glass jar of marbles from the Opening. Between each sample, all marbles will be replaced in the jar before the next sample is selected.

Do the following:

- For each group of five samples of different sizes, find the mean number of marbles for each color.
- Determine the number of marbles for each color in the jar, based on the mean you calculated for each color.

Samples:

- Draw 5 samples of 10 marbles each.
- Draw 5 samples of 50 marbles each.
- Draw 5 samples of 100 marbles each.

- Remember, the
*mean*is the average of the data set.

Think about these questions as part of your presentation.

- Within each sample size group, how do your results compare for the five samples? What does this comparison tell you?
- How do your results compare for the three sample size groups?
- How many marbles of each color do you think there are in the jar?

- If the jar held 500 marbles but had 10 different colors of marbles, what do you think the best sample size would be?

INTERACTIVE: Marble Jar

Take notes about the approaches your classmates used to determine the number of each color of marble in the jar.

As your classmates present, ask questions such as:

- How do your results compare for the five samples within each sample size group?
- How do your results change as the sample size increases?
- How are the numbers of each color marble related to each other, if at all?
- Could the results of each sample within the same sample size group have been added together to make one big sample? Why or why not?
- Which sample size do you think is the best?

Write a summary about making conclusions about populations based on samples and the affect of sample size.

Check your summary:

- Do you discuss how you can determine characteristics of a population based on samples?
- Do you explain how sample size affects the conclusions you make about the population?

Write a reflection about the ideas discussed in class today. Use the sentence starter below if you find it to be helpful.

**When I think about probability and sampling, I see these connections...**