# statistics

## Project Description:

q1: a recent study of 50 self-service gasoline stations in the lubbock area revealed that the mean price of unleaded gas was \$1.22 per gallon and the standard deviation was \$0.04 per gallon.

a.what is the point estimate? explain what it indicates.

b.using the .99 percent degree of confidence, determine the confidence interval for the population mean. explain what it indicates.

q2: the following paired sample observations are scores for six students chosen at random from lubbock high school. the "before" scores represent their knowledge of english literature before they studied the subject for a 2-week period. the "after" scores are their scores after studying english literature for 2 weeks:

student 1 2 3 4 5 6
before 65 72 55 66 82 90
after 80 78 57 76 91 85

at the .05 significance level, can we conclude that there has been an increase in knowledge (as indicated by this exam) as a result of the two-week period of study?
show all 5 steps and explain your conclusion.

q3: a test measuring the knowledge of the u.s. constitution has been given to a national sample of 6000 high school seniors. the distribution of scores approximates the normal curve and has a mean of 79 and a standard deviation of 6.5.

a.what percentage of those tested scored 68 or below?

b.how many of the 6000 individuals scored between 68 and 87?

c.i want to give the top 7% of the students a prize for doing such a great job on the exam. what would be the lowest score eligible for a prize?

q4: your supervisor dumped a box of sales information regarding your company and then asked you to make sense of it. you went through the information and compiled the following list of this year's weekly sales (in \$1,000's). your job now is to organize and summarize the information.

6 8 4 6 5 10 11 5 2 3
6 5 7 8 7 4 4 5 7 6

be sure to show all work! i am not able to award partial credit for wrong answers with no supporting computations.

part i:

a.using the raw data, what is the
1) mean,
2) median,
3) mode,
4) range,
5) variance and standard deviation?

part ii:

a.organize these scores into a frequency distribution using 5 classes, beginning with “0”. please show relative frequencies.

b.construct a
1) histogram,
2) frequency polygon,
3) more-than cumulative frequency polygon.

based on your more-than cumulative frequency polygon, approximately how many weeks had sales of \$6500?

c.comment on the shape of the distribution. use statistical

d.ignore part “c” above and assume the data are normally
distributed. based on this assumption, approximately 95% of your
organization’s sales were between \$_____ and \$_______ (use the
empirical rule).

e.what conclusions might one draw from this information?
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Price Type: Negotiable

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