If we have a standard deviation of 10 and a sample size of 25, what is the standard error of the mean?
A teacher decides to give a standardized test to her students to find out how much they know about stats before starting an introductory statistics course. The test has a mean score of 100 and the standard deviation of 20. Using this information, determine the percentile rank for students based on what percentage of students the student of interest did better than with the following scores.
a. Score of 80:
b. Score of 140:
A local pharmaceutical company wants to determine if the local community is or is not in favor of a public health care option. A recent poll indicates that 60% of the community is in favor of this plan. Given that the standard error is 1.2, construct a 95% confidence interval for this measurement including upper and lower limits. What can we conclude of this?
Now we will say that a later poll indicates 52% are in favor. We will say the standard error in this case is 2. If the z-score is 1.96, calculate a 95% confidence interval based on this new information.