The average score on a statistics test is 70%. The standard deviation is 10%. 

What is the minimal test score that Judy needs in order to reach the 90^th percentile?

Our final sales figures (in millions) for the year are:

Use Excel to calculate the correlation coefficient between the month number

etc.

and the sales figure(s).

Also, compute the  value for testing the confidence level for the correlation coefficient.

Our final sales figures (in millions) for the year are:  

Using the above data, calculate the regression line

that best fits the data. 

Hint – make the month number

etc.

the independent variable  and make the sales figure the dependent variable . Use Excel to calculate the slope.

The average sales price of a home in Ourtown U.S.A. is $120,000.

The population standard deviation is $20,000. 

What is the probability that the next home will sell for more than $130,000?

We are trying to determine the average age of the Cardinal baseball fan. We know that the age distribution of Cardinal nation is normally distributed with a standard deviation of 20. We need to determine the average age. We take a sample of 40 fans and the average of our sample is 42 years old. 

What is the 95% confidence interval (range) for our sample average of 42? (remember – confidence intervals are always 2- tailed (plus or minus)).

We are trying to determine the average age of the Cardinal baseball fan. We know that the age distribution of Cardinal nation is normally distributed with a standard deviation of 20. We need to determine the average age. We take a sample of 40 fans and the average of our sample is 42 years old. 

However, the Cardinal President of Operations wants a 98% confidence interval of plus or minus 5.0. What sample size do we need to satisfy his request?

The Cardinals average 4 extra inning games per month. 

What is the probability that they will have more than 4 extra inning games next month? Hint – Poisson distribution.

A real estate tycoon wants to test the hypothesis that the percentage of people who own their own home in Florida is the same as the home ownership percentage in Georgia. He states his null hypothesis as 'the Florida percentage is the same as the Georgia percentage' and the alternative hypothesis is 'the percentages are significantly different'. He decides on a 2-tailed test and he samples 400 Florida homes and 600 Georgia homes. His sample results:

Florida - 280 homeowners out of 400 (.7)

Georgia - 384 homeowners out of 600 (.64)

a percentage difference of .06

What is the lowest confidence percentage that will support his rejection of the null hypothesis? Stated another way – what is the highest percentage that will support his acceptance of the null hypothesis?

The average age of our customers is 40 years with a standard deviation of 10 years. 

What is the probability that the next customer to enter our store will be between 30 and 50 years old ?

The Z Table is the cornerstone of intro stats. It translates the 'number of standard deviations from the mean' into a percentile (.90, .95. .99. etc.). The table is laid out with the assumption that the test being conducted is a 'one-way' test, meaning that the Z value is greater than some percentile (if Z is positive) or less than some percentile (if Z is negative). Another way of saying this is: the Z table only measures the area under the curve for 1 of the 'tails' (either the extreme right or the extreme left). So, if we have a 2 tailed test for say 95% confidence, then we must put 2.5% in our right tail and 2.5% in our left tail. Conversely, a one tailed test for 95% puts 5% in the right tail only. 

Arrange the 5 following confidence intervals in ascending (lowest to highest) order of their Z value:

A) 2 tailed test at 95%

B) 1 tailed test at 95%

C) 1 tailed test at 90%

D) 2 tailed test at 99%

E) 1 tailed test at 99%