9. To evaluate the effect of a treatment, a sample is obtained from a population with a mean of pu = 30, and the treatment is administered to the individuals %3D in the sample. After treatment, the sample mean is found to be M = 31.3 with a standard deviation of s = 3.

A test was administered for a group of 400 students and scores were obtained. The scores are approximately normally distributed with a mean of 65 and standard deviation of 4.5. What are the scores within which approximately 95% of the total test scores fall?

A simple random sample of 36 observations was taken from a large population. The sample mean and the standard deviation was determined to be 80 and 12 respectively. What is the standard error of the mean?

The scores on a standardized test are normally distributed with a mean of 120 and standard deviation of 5. What test score is 1.1 standard deviations above the mean?