Candy Machine

Planning for College Independent: Because the school district is large, we can assume that there are more than 10(125) = 1250 middle school students. Normal: We can consider the distribution to be approximately Normal since np = 125(0.80) = 100, which is greater than 10 and n(1 – p) = 125(0.20) = 25, which is greater than 10.

Planning for College Do: normalcdf(0.73, 0.87, 0.80, 0.036) = 0.948. (Note: To get full credit when using normalcdf on an AP exam question, students must explicitly state the mean and standard deviation of the distribution as in the Plan step above.) Conclude: About 95% of all SRSs of size 125 will give a sample proportion within 7 percentage points of the true proportion of middle school students who are planning to attend a four-year college or university.

Harley’s p= 0.14 Standard Deviation= Independent: It is reasonable to assume there are more than 5000 motorcycle owners. Normal condition: np = 500(0.14) = 70 and n(1-p) = 500(0.86) = 430 and are both at least 10. Normalcdf (0.2, 1, .14, 0.0155) = 0.000057 While it is possible, it is extremely unlikely that we would get a sample of 500 motorcycle owners in which at least 20% own Harleys.