1) Get a Bag of Foam Pieces and a Paper Bag from Mrs. Mcnelis

NAME: ______Activity 5.2B

1)  Get a bag of foam pieces and a paper bag from Mrs. McNelis.

2)  In your bag, there are 160 pieces: 40 of color1 and 120 of color2. This is your population.

3)  Pour the pieces into the paper bag. Shake up the pieces.

4)  We are interested in color1 (the one that has the 40 pieces).

5)  What is p (the pop. proportion of color1)? ______

6)  Reach into the paper bag and take a sample of 20 pieces and count the number of color1. Calculate (the sample proportion of color1), as a decimal (# color1 20). Record it on the first line below. Then go to #7.

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7)  Return the sampled pieces to the paper bag, and shake well. Repeat your sample of 20, calculate the proportion, and record it on the lines above. Do this until you have a total of 8 samples.

8)  What is your average? ______Is this close to p?

9)  Record all 8 of your on the board. BE SURE TO RECORD YOUR DATA IN THE RIGHT SPOT (your sample size- there are 2 different sample sizes).

10)  Enter the class data (FOR YOUR SAME SAMPLE SIZE) into your calculator in a list.

11)  Create a histogram of your sample’s class data below. Use an Xmin = 0 and Xscl = 0.05 for the window. Also calculate the average and standard deviation.

12)  How does your class average compare to the true proportion (0.25)? Close, far??

13)  Now get a partner who took the other size sample (n = 5). Copy their histogram below:

14)  Comment on the differences between the histograms. Both plots are created on the same scale. What are the major differences? How does the sample size affect the plots?

15)  What do these two plots show us about sampling variability?