14. Recognizing clusters within your data, and segmenting the data for more insightful analysis, is a process of trial and error. Suppose you have data on your customers by spending amounts, age, their estimated annual income, as well as whether they reside east of the Mississippi River or west of the Mississippi River.

You are testing the hypothesis that east of the River spend more on average, than west of the River. As the researcher, you are hoping that west of the River spends more. You wish to be 95% sure before you state your hypothesis challenge to upper management. You have sampled 100 east River customers and 150 west River customers. East River has a standard deviation of $2,000 and an average of $11,000 in annual spending on your goods/services. West River has a standard deviation of $4,000 and an average of $14,000.

Calculate your Z-value. No need to reject/not reject the hypothesis here, but you do know the bigger the Z-value, the better chance you have to reject. Hint: When calculating your Z-value, the East River average the West River average is how you set up your numerator. You are hoping for a negative Z-value in this hypothesis test.