Name(s)                                                                     :
Sampling Distributions and Variability
Introduction to Statistics, Fall 1999, Tom Linton
  1. Take your collection of M&Ms and count out the "first" 25 of them. Divide (randomly) the remaining M&Ms into groups of size 10. Once you have less than 10 remaining, you may eat the leftovers (the last group of less than 10).
  2. We are interested in estimating two quantities, the percentage of M&Ms which are yellow and the percentage of M&Ms which are brown. To accomplish this, we will count the number of yellow M&Ms in our piles of size 25 and the number of brown M&Ms in each pile of size 10.
    1. What two parameters are involved in this process?




    2. Describe the two statistics we will use to estimate the parameters in part (a).




  3. Record the proportion of yellow M&Ms in your group of size 25.                             :


  4. In the table below, record the proportion of brown M&Ms in each group of size 10.
Brown M&M Proportions
Group 1 2 3 4
Proportion        
  1. Add your proportions to the class data stem and leaf plots and then copy these stem and leaf plots below.











  2. Are the stem and leaf plots symmetric? 

  3. Do they appear approximately normal? 

  4. Which is more spread out?

  5. Estimate the mean of each stem and leaf plot.

    brown mean = 

    yellow mean =




  6. Calculate the mean and standard deviation of both the proportions of brown and yellow M&Ms based on the class data sets.





  7. Using Table B, select a SRS of size 4 from the proportions of yellow M&Ms. Record the yellow proportions you selected and the mean of your 4 yellow proportions below. Add your 4-proportion mean to the stem and leaf plot on the board.

    yellow proportion numbers in our SRS:

    mean of 4 proportions = 


  8. Calculate the mean and standard deviation of this new data set.