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The advertisement for a hardware store chain included a coupon for a 20% discount on a wide variety of products. The numbers of coupons that were used the following week in all of the chain's 40 stores are listed here.

Draw an ordered stem & leaf plot of the data above.

Draw a histogram.

For the tabulated data calculate the following: mode, median, first and third quartile, the interquartile range, the mean and the standard deviation.



Mode

15%

Median

22%

First Quartile

35%

Third Quartile

25%

Interquartile Range

70%

Mean

65%

Standard Deviation

33%

You have been told that the data has a normal distribution. Do you think that this is so? (Circle your answer)

YESNONOT SURE

Give reasons for your answer in d.

Because data have no normal distribution.

For the following statements about correlation and regression circle T if the statement is True and F if the statement is False.

a) It is impossible for different data sets to give the same regression equation and the same coefficient of determination.

F

b) In a simple regression the coefficient of determination is 81% and this means that the correlation coefficient is 0.9.

T

c) I have five data points from 2 variables. The correlation coefficient is 0.75. This correlation coefficient is significant at the 5% level.

T

d) Correlation coefficient are very useful, they tell me all I need to know about the relationship between the two variables concerned.

F

e) If two variables are positively correlated, then as the values of one variable fall, the value of the other variable rise.

T

f) If the relationship between the two variables is very negative you may get a correlation coefficient that is less than -1.

F

g) p value is the probability of having a test statistic the same as the observed one from your sample.

T

h) When you are certain of your line it is ok to extrapolate outside of the range of the data from which the model was constructed.

T

i) If the correlation coefficient is zero, it mean there is no association between the two variables concerned.

F

j) Primary data sources include published industry reports, newspapers and government statistics etc.

T

Look at the following 4 problems and for each state probability distribution which is best for dealing with the problem. Give reasons for your choice. Calculate the probability in each case.

The mean number of users of an automatic banking machine is 1.5 in a 5-minute interval. Find the probability of the following events:

No users in the next hour.

5 or fewer users in the next 15 minutes.

3 or more users in the next 10 minutes.

World Oil conducts exploratory oil drilling operations in Russia. Each well drilled is classified as a producer well or a dry well. Past experience shows that this type of exploratory operation provides producer wells for 30% of all wells drilled. Bonus payments to staff are related to the profitability of each hub consisting of 8 wells. Suppose 8 wells are randomly selected to form a hub.

Calculate the probability that out of the 8 wells exactly 5 will be producer wells.

What is the probability that none of the wells will produce oil?

In order for bonus payments to be made, ...