Statistics Practice Questions

Problem 1: Skewed Movie Going Distributions

1. The number of times MU students went to the movies last year is positively skewed with a mean of 4.5 and a standard deviation of 1.4. At least what percentage of students went to between 2 and 7 movies last year? 

2. Suppose you want to select three people to form a committee from a group of 12 people. How many groups of three are possible?

3. A study showed the carbohydrate intake of teenage males follows a distribution that is mound-shaped and symmetric (approximately normal) with a mean of 124 g/1000 calories and a standard deviation of 20 g/1000 calories. Find a carbohydrate level for which 97.5% of carbohydrate intakes exceed that level? That is, 97.5% of carbohydrate levels for teenage males exceed g/1000 calories. 

4. SAT scores have a mean of 1026 with a standard deviation of 209. ACT scores have a mean of 20.8 with a standard deviation of 4.8. A student takes both and scores 900 on the SAT and 19 on the ACT. On which test did the student do relatively better? 

5. A car manufacturer recorded complaints about a new model of car and found they fell into the six categories in the table below.

If we randomly select a complaint, what is the probability it is after the guarantee period (A) or about an electrical problem (E)? (

6. A car manufacturer recorded complaints about a new model of car and found they fell into the six categories in the table below. 

If we randomly select a complaint, what is the probability it is during the guarantee period (D) and about a paint problem (P)?

7. The ages listed below are for a random sample of 5 kids attending a junior golf camp:

7 9 6 8 9

Find the sample median

8. The ages listed below are for a random sample of 5 kids attending a junior golf camp:

7 9 6 8 9

Find the sample standard deviation