STAT 10 PRACTICE MIDTERM

1. A sample of five pulse rates is 65, 80, 78, 72, 55. Determine the median pulse rate.

A. 67.5

B. 70

C. 72

D. 78

2. Which one of the following statistics measures variation or spread?

A. Minimum

B. Median

C. Mean

D. Standard deviation

3. Which of the following statements is true about a symmetric distribution ?

A. The mean and median will be about the same

B. The mean will be noticeably larger than the median

C. The median will be noticeably larger than the mean

4. A list of eight sores on a test of anxiety is 88, 56, 70, 90, 64, 60, 76, 84 .

Determine the first quartile (25th percentile).

A. 60 B. 86 C. 74 D. 62

5. Scores on a verbal achievement test have a histogram that looks like a bell

curve. The mean score is 100 and the standard deviation is 20.

(a ) Which choice best fills in the blank? About 95% of the achievement test scores will be between _____.

A. 80 and 120 B. 60 and 140 C. 40 and 160 D. 98 and 102

(b) What percentage of the scores are higher than 110 ?

A. 50 B. 69 C. 31 D. 25

(c) Which of the following scores is approximately in the 16th percentile of the achievement scores ?

A. -1 B. 95 C. 120 D. 80

6. Classify each of the following variables as Qualitative (QL) or Quantitative (QT) and if is Quantitative identify it as Discrete (D) or Continuous (C)

7. A student scores at the 70th percentile on a verbal achievement test. Which of the following statements best explains what this means ?

A. The student's score was 70 % .

B. The student scored higher than 70 % of the other test takers.

C. The student scored lower than 70 % of the other test takers

D. The student's score was the same as 70 % of the other test takers.

8. A sociologist conducted a study on the effects of two teaching styles. One style was Authoritarian (A) with strict discipline and many rules. The other style was more Democratic (D) where students were given fewer restrictions and encouraged to set their own standards of conduct. Comparing standardized tests scores before and after the teaching techniques were introduced, she found the following:

ALL STUDENTS

When she disaggregated the data into class in school, that is: Freshmen and Sophomores versus Juniors and Seniors she was surprised to see the following:

FRESHMEN AND SOPHOMORES

JUNIORS AND SENIORS

Which is the confounding variable?

A. Teaching Style

B. Percentage Improved (far right column)

C. Class in School

D. None of the above, there is no confounding in these tables

9 A Die is rolled 4 times. What is the chance that none of the rolls show 4 or more spots?

A. less than 1%

B. 1.20%

C. 6.25%

D. 50%

E. 93.75%

10. A Company is planning a new investment. The amount of profit is uncertain, but a statistical consultant has produced a table (or box -- hint ) of the probabilities associated with different projected profit estimates (in millions of dollars):

Find the expected average profit.

A. 2 million

B. 3.7 million

C. 18.5 million

D. 74 million

(extra practice) Find the standard error associated with this profit.

11. A box contains red and blue marbles; there are more red marbles in the box than blue ones. Marbles are drawn one at a time from the box, at random, with replacement. You win a dollar if a red marble is drawn more often than a blue one. There are two choices:

(A) you get to draw 50 marbles from the box

(B) you get to draw 100 marbles from the box

Which is of the following statements is correct:

A. (A) gives a better chance of winning

B. (B) gives a better chance of winning

C. (A) and (B) have the same chance of winning

D. (B) gives twice the chance of winning that (A) does

E. There is not enough information to answer this question.

12. An astronaut's oxygen supply comes from two independent sources.

Source A has a 90% chance of working and Source B has a 80% chance of working.

What is the chance that at least one of the sources will be working?

A. 72%

B. 80%

C. 90%

D. 98%

E. There is not enough information to calculate the chance.