Name:



Name: _________________________________ Mean & Variance WS

AP Statistics

For questions 1-3, try not use a calculator.

1) A list has 10 numbers. Each number is a 1, 2, or 3. The average is 2 and the standard deviation is 0. What are the 10 numbers?

2) Three instructors are comparing scores on their finals; each had 99 students. In class A, one student scored 1 point, another scored 99 points, and the rest scored 50 points. In class B, 49 students scored 1, one student scored 50, and 49 students scored 99. In class C, one student scored 1, another scored 2, another 3, and so forth, all the way through 99.

a) Which class had the biggest average? Smallest average?

b) Which class had the biggest SD? Smallest SD?

c) Which class had the biggest range? Smallest range?

3) Each of the following lists has an average of 50. For each one, guess whether the SD is around 1, 2, or 10.

a) 49, 51, 49, 51, 49, 51, 49, 51, 49, 51

b) 48, 52, 48, 52, 48, 52, 48, 52, 48, 52

c) 48, 51, 49, 52, 47, 52, 46, 51, 53, 51

d) 54, 49, 46, 49, 51, 53, 50, 50, 49, 49

e) 60, 36, 31, 50, 48, 50, 54, 56, 62, 53

4) In a manufacturing process, there are three stages. The average run-time for stage one is 5.6 minutes with a standard deviation of 1.2 minutes. The mean run-time for stage two is 12.3 minutes with a standard deviation of 3.8 minutes, and, for stage three, the mean is 6.4 minutes with a standard deviation of 2.8 minutes. What is the mean and standard deviation of the entire process?

5) A student was performing an experiment that compared a new protein food to the old food for goldfish. He found the mean weight gain for the new food to be 12.8 grams with a standard deviation of 3.5 grams. Later he realized that the scale was out of calibration by 1.5 grams (meaning that the scale weighed items 1.5 grams too much). What should the mean and standard deviation be for the new food?

6) Girls at GBHS have an average height of 65.5 inches with standard deviation of 2.3 inches. Boys have an average height of 71 inches with standard deviation of 3.5 inches. If girls and boys were picked at random and the difference in height (boys – girls) calculated, what would the average height difference be? What would the standard deviation of the differences in height be?

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download