We may test a null hypothesis using a confidence interval. The following would be our rule. We take a sample of 16 individuals from a population of students and record their grade point averages. The mean is 2.10 and the standard deviation 0.5. Interpret the confidence interval.
Grades are from a normal distribution with the same mean and variance for all students.
The students are sampled at random - thus, their grades are completely independent. Assuming that weights are normally distributed with a true mean of 140 pounds for males, and a standard deviation of 15 pounds in a large college student population. In problem 3 above what is the probability that the mean weight of 9 students chosen at random is greater than 140 pounds 0.50 5. We sample 4 trees with replacement. We now are interested in seeing if the oaks in the forest are randomly distributed among the trees in space.