# Standard Deviation

In a study of quantities of rice consumed in two different cities, a sample data looks as in the attachment. Sampling units were families of four, data is for a year.

a. Would it be reasonable to conclude (95 percent confidence) that the two cities were statistically different in the average quantities of rice they consumed per year? Why?

b. If it were desired to combine the two samples into a general model of rice consumption, how small (to the nearest integer) would the joint standard deviation have to be to make such a combination if the 95 percent confidence limit were to be preserved.

c. Is the appropriate test to use in both of the above cases the one-tailed or the two-tailed test? Why?

https://brainmass.com/statistics/hypothesis-testing/sample-standard-deviation-29721

#### Solution Preview

Solution is attached.

a) Since the sample sizes are very large, we can use z-test. WE know that

City A City B

Sample mean 210lbs 235lbs

Sample Std error 20lbs 25lbs

Joint Std error ...

#### Solution Summary

In a study of quantities of rice consumed in two different cities, a sample data looks as in the attachment. Sampling units were families of four, data is for a year. The solution answers multiple questions regarding statistics and provides a brief discussion on each.