We are interested in estimating the average driving time of students who commute to Ohio State.  How many students who commute need to be included in our sample to order to be 98% confident that the estimated mean driving time will be within 4 minutes of the true population mean driving time if the standard deviation of the driving times is 8 minutes?

The  ∑  symbol in a statistical equation indicates that we are to perform which arithmetic operation?

A study was conducted to determine whether a student’s final grade in a high school math class is linearly related to his or her performance on the math ability test administered before college entrance.  The math test scores and final grades for a random sample of 10 students are shown below. Final Grade in Math Class (X)          Math Ability Test Score (Y) 65                                                             39 78                                                             43 52                                                             21 82                                                             64 92                                                             57 89                                                             47 73                                                             28 98                                                             75 56                                                             34 75                                                             52 Find the covariance between the final grades in the math class (i.e., variable X) and the math ability test scores (i.e, variable Y).

The following table shows litter sizes for sows in four breeds of pigs. Yorkshire     Landrace     Hampshire     Duroc      8                   9                   8                 7     10                  9                   7                 8     11                10                   8                 9     11                10                   9                 7       9                  8                                                 49                46                 32               31 – treatment totals     9.8               9.2               8.0              7.5 – sample means     The total sums of squares in the Analysis of Variance table for this problem is equal to ____________.                                                                                    

The grades of 8 students on an exam were as follows: Student Grade 1 66 2 70 3 64 4 88 5 74 6 72 7 87 8 79     Find the mode for the grades of these 8 students.

A vet clinic has found that the number of patients per day has an average of 100 and a standard deviation of 10.  If nothing is known about the shape of the distribution of number of patients seen per day, what percentage of the days would be expected to have between 70 and 130 patients?

Which one of the following is not an assumption when we perform an Analysis of Variance?

A dairy producer in Ohio wants to determine if the average milk production of her Holstein cows is greater than 18,000 lb of milk per lactation.  Therefore, she obtains a random sample of n = 100 milk production records from her herd and calculates a sample mean of 18,500 lb and a sample standard deviation of 3,500 lb. Calculate the test statistic needed to test the null hypothesis.

Toyota would like to know how many miles per gallon the average person gets when driving the hybrid Toyota Prius.  A random sample of 225 drivers yields a mean of 50 mpg and a standard deviation of 7.5 mpg.  Find the 90% confidence interval for the population mean for the miles per gallon of the Toyota Prius.

The birth weights in pounds of a sample of 7 calves were as follows: Calf Weight 1 68 2 70 3 64 4 90 5 74 6 72 7 87         Find the variance of the birth weights of this sample of 7 calves.