1. Which of the following statements are correct? 1. A normal distribution is any distribution that is not unusual. False 2. The graph of a normal distribution is bell-shaped. True 3. If a population has a normal distribution, the mean and the median are not equal. False 4. The graph of a normal distribution is symmetric. True Using the 68-95-99.7 rule: 34-47.5-49.58
Assume that a set of test scores is normally distributed with a mean of 100 and a standard deviation of 20. Use the 68-95-99.7 rule to find the following quantities:
Suggest you make a drawing and label first… http://my.ilstu.edu/~wjschne/138/Psychology138Lab7.html 40 60 80 100 120 140 160 1. Percentage of scores less than 100: 50% 2. Relative frequency of scores less than 120: 84% 3. Percentage of scores less than 140: 97.5% 4. Percentage of scores less than 80: 16% 5. Relative frequency of scores less than 60: 4.5% 6. Percentage of scores greater than 120: 16% 2. Assume the body temperatures of healthy adults are normally distributed with a mean of 98.20 °F and a standard deviation of 0.62 °F (based on data from the University of Maryland researchers). 1. If you have a body temperature of 99.00 °F, what is your percentile score? 447 z score= (x-)/
(99-98.2)/.62= 1.29 1.3
90.15 percentile 2. Convert 99.00 °F to a standard score (or a z-score). 447 z score= (x-)/
(99-98.2)/.62= 1.29

3. Is a body temperature of 99.00 °F unusual? Why or why not? I wouldn’t say unusual, but somewhat abnormal as it is 1.29 standard deviations from the mean. 4. Fifty adults are randomly selected. What is the likelihood that the mean of their body temperatures is 97.98 °F or lower? 446 z = (97.98-98.2)-.62= -2.5091