A random sample of 51 observations was selected from a normally distributed population. The sample mean was = 88.6, and the sample variance was s2 = 38.2. Does the sample show sufficient reason to conclude that the population standard deviation is not equal to 8 at the 0.05 level of significance? Use the p-value method.
A researcher wishes to compare two different groups of students with respect to their mean time to complete a particular task. The time required is determined for each group. The data summary is given below. Test the claim at = 0.05, that there is no variance. Give the critical region, test statistic value, and conclusion for the F test.
n1=100, s1=20
n2=120, s2=34
The number of sit-ups that a person can do in one minute, both before and after a physical fitness course was recorded. The data is shown below for 10 randomly selected participants. Is there sufficient evidence to conclude that a significant amount of improvement took place? Assume variable is normally distributed.
Before 30 23 25 29 27 25 30 45 34 26
After 31 27 25 35 34 35 32 52 50 43