Statistics and Probability Answers

A professor grades student on 4 tests, a term paper, and a final examination. Each test counts as

15% of the course grade. The term paper counts as 20% of the course grade. The final

examination counts as 20% of the course grade. Alan has test scores of 80, 78, 92 and 84. Alan

received an 84 on his term paper. His final examination score was 88. Use the weighted mean

formula to find Alan’s average for the course. Hint: The sum of all weights is 100% = 1.

Box A and Box B both contain the numbers 1,2,3, and 4. Construct the probability mass function and draw the histogram of the sum when one number from each box is taken at a time, with replacement

1. If the height of adults in Illinois State University can be modelled using H~ N(174,35.7). Where the height is measured in centimeters

a. What type of data is this? (4 points)

b. What is the probability that a randomly selected adult from the University has height between 166 and 183? (14 points, show your work)

Briefly explain different data presentation techniques.

Construct a frequency distribution of weights of miniature poodles if the class marks

are 6.5, 8.5, 10.5, 12.5 and 14.5 kgs with corresponding frequencies 8, 12, 22, 17 and 3.

Classify each of the following first as qualitative or quantitative and second as nominal,

ordinal, interval or ratio measure.

a) temperatures of 22 selected refrigerators

b) hair color of women on a high school tennis team

c) numbers on the shirts of a girl’s soccer team

d) ages of students in a statistics class

e) number of pages in your statistics book

f) list of 1247 social security numbers

g) the ratings of a movie ranging from “poor” to “good” to “excellent”

h) the final grades (A,B,C,D, and F) for students in a chemistry class

i) the nationalities listed in a recent survey

j) the amount of fat (in grams) in 44 cookies

Classify the following sentences as belonging to the area of descriptive statistics or

inferential statistics.

a) As a result of recent cutbacks by oil-producing nations, we can expect the price

of gasoline todouble in the next year.

b) At least 5% of all killings reported last year in city X were due to tourists.

c) Of all patients who received this particular type of drug at a clinic Y, 75%

later developedsignificant side effect.

a) The average age of the students in a statistics class is 21 years.

b) Adane concludes that his chance of passing the first year this academic year is at

least 80% basedon the statistics that 75% of the freshmen passed last year.

A box contains 8 balls. One is numbered 2, two are numbered 3, one is numbered 4, and four are numbered 5. The balls are mixed and one is selected at random. After a ball is selected, its number is recorded. Then it is replaced. If the experiment is repeated many times, find the variance of the numbers on the balls. (Round off your final answer to 2 decimal places).

A certain store has four ways of handling returns: cash refund, credit to account, exchange, or refusal. The manager claims that the four ways are equally probable to test this hypothesis, 108 customers were sampled with the following results 

Type

Cash

Credit

exchange

Refusal

Count

34

27

32

15

 Does the data support the managers claim at 5 %.                                                              (6mk

It is the most common model for relative frequencies of a continuous random variable.