Statistics and Probability

| Direction: Identify the appropriate test statistic to be used in each problem. Write z-test or t-test on the space provided. 1. A sample of n=25 is selected from a normal population, x= 56 and s= 12. 2. Based on the report of the school nurse, the average height of Grade 1 1 students has increased. Five years ago, the average height of Grade 1 1 students was 170cm with standard deviation of 38cm. She took a random sample of 150 students and derived the average height of 165cm 3. Knowing from a previous study that the average of athletes is 80, an athletic adviser asked how his soccer players are academically doing as compared to other student athletes, After an initiative to help improve the average of student athletes, the adviser randomly selected 15 soccer players and found 85 as the average with standard deviation of 1 25. 4. The CEO of a battery manufacturing company claimed that their batteries would last an average of 280 hours under . normal use. A researcher randomly selected 20 batteries from the production line and tested them. The tested batteries had a mean life span of 250 hours with a standard deviation of 40 hours, Do we have enough evidence to suggest that the claim of an average of 280 hours is false? II Directions: Find the rejection region and critical value for each hypothesis test based on the information given. 1. Ho [=121 Hap >121 a=0.01 n=39 a known 2. H. (1 98 6 Ha u #98,6 0 0.05 n 25 0-unknown