The candy company claims that 10% of the M&M’s it produces are green. Suppose that the candies are packaged at random in small bags containing about 50 M&M ‘s. A class of elementary school students learning about percents opens several bags, counts the various colors of the candies, and calculates the proportion that are green. a) If we plot a histogram showing the proportions of green candies in the various bags, what shape would you expect it to have? b) Can that histogram be approximated by a Normal model? Explain. c) Where should the center of the histogram be? d) What should the standard deviation of the proportion be?
a) A bell shape
b) If we have several students (more than 30) histogram must be near a Normal Model
c) At p = 0.1
d) If n =number of bags then standard deviation of proportion should be sqrt(P*(1-p)/n)= sqrt(0.1*0.9/n) = sqrt(0.09/n)