1. the mean score on a college placement exam is 450 with a standard deviation of 75. a) what percentage of students the exam score below 400? b) what percentage of students score above 550? c) if 1500 students take the exam how many of them will score below 440? 2. a factory dumps an average of 2.87 tons of pollution into a river every week. if the standard deviation is 0.76 tons, what is the probability that in a week more than 3 tons are dumped? 3. erin is taking two ap classes. in physics, she scored an 82. the class average was 77 and the standard deviation was 5.5. in stats, she scored an 88. the class average was 81 and the standard deviation was 9.6. relatively speaking, on which test did she perform better? explain your answer. 4. the average time it takes a high school swimmer to complete the 100-meter butterfly is 54 seconds with a standard deviation of 3.5 seconds. what percentage of swimmers complete the race in over one minute? 5. cholesterol levels in the blood of 14-year old boys are normally distributed with mean µ = 170 milligrams of cholesterol per deciliter of blood. the standard deviation is σ = 30 mg/dl. a) what percent of 14-yr old boys have a cholesterol level between 130 and 180 mg/dl? b) a cholesterol level above 240 requires medical attention. what percent of 14-yr. old boys have a cholesterol level that requires medical attention? 6. in order to be considered for membership in a college honor society a student must have a gpa in the top 3% of the student body. if the mean gpa of all students is 3.2 with a standard deviation of 0.25, what is the minimum gpa a student must have in order to be consider for the honor society?