Statistics and Probability Answers

For items 9 to 10, refer to the given table below.

Mathematics Quiz Scores of 15 Grade-10 Aphrodite Student

Name Score

Amy 17

Michelle 17

Aila 17

Evan 11

Albert 11

D-anne 16

Sarah 15

Isaac 18

Aidan 19

Carl 12

Cherry 17

Jethro 14

Angelo 16

Nica 18

Noah 15

9. If 1 is 12, how many students belong to the lowest 25%?

10. If 5 is 16, how many students belong to the lower 50%?

Lilian got a score of 55, which is equivalent to the 70th percentile in a mathematics test. Which of the following is NOT true?

A. 70% of the students got a score less than or equal to Lilian’s score.

B. Thirty percent of the class got scores of 55 and above.

C. If the passing mark is the first quartile, she passed the test.

D. Her score is below the 5th decile.

3. The set of scores: 15, 14, 12, 10, 9, 11, 17, 15, and 19, find the median score.

M. 9 T. 11 A. 10 H. 14

2. What do you call the ninety-nine score points which divide a distribution into one hundred equal parts? M. decile T. percentile A. median H. quartile

The purchasing director of an industrial part factory is investigating the possibility of purchasing a new type of milling machine. He determines that the new machine will be bought if there is evidence that the parts produced have a higher mean breaking strength than those from the old machine. The population standard deviation of the breaking strength for the old machine is 10kg and for the new machine is 9 kg. A sample of 100 parts was taken from each machine. Old machine indicates a sample mean of 65kg while new machine indicates a sample mean of 72 kg. Using the 0.01 level of significance, is there evidence that the purchasing director should buy the new machine? (critical value = + 2.575 )

The average length of time for students to register for summer classes at a certain college has been 50 minutes. A new registration procedure using modern computing machines is being tried. If a random sample of 35 students had an average registration time of 42 minutes with a standard deviation of 11.9 minutes under the new system, test the hypothesis that the population mean is now less than 50 minutes, using a level of signficance of 0.01. (critical value = +/- 2.33)

7. Calculate P40 of the judges’ scores.

M. 8.12 A. 8.42 T. 8.75 H. 9.10

The scores of Miss San Quintin candidates from seven judges were recorded as follows: 8.12, 9.10, 8.42, 9.14, 8.75, 9.17, and 8. 37

For numbers 4 – 6, refer to the given data above.

4. Find the 50th percentile or P50 of the judges’ scores.

M. 9.14 A. 8.75 T. 8.42 H. 8.12

5. What is the P30 of the judges’ scores?

M. 9.10 A. 8.75 T. 8.42 H. 8.37

6. Determine the 70th percentile of the judges’ scores.

M. 9.14 A. 9.10 T. 8.42 H. 8.12

1. Which of the following is the same as the median score? M. 2 nd quartile T. 25th percentile A. 6 th decile H. 75th percentile

2. What do you call the ninety-nine score points which divide a distribution into one hundred equal parts? M. decile T. percentile A. median H. quartile

3. The set of scores: 15, 14, 12, 10, 9, 11, 17, 15, and 19, find the median score. M. 9 T. 11 A. 10 H. 14

A recent study by the American Accounting Association revealed among 30 graduates in accounting 20 students graduating with a major in accounting select public accounting. Suppose we select a sample of 15 recent graduates.

A. What is the probability that exactly two select public accounting?

B. What is the probability that exactly five select public accounting?