We want to test the hypothesis that the mean number of credit hours taken per semester by OSU undergraduates is less than 16 hours.  Therefore, we obtain a random sample of credit hours for 49 students. The sample mean is 15 hours and the sample standard deviation is 4 hours.  We want to test:    Ho:  μ = 16 hours    Ha:  μ < 16 hours using a significance level (α) = 0.01. What is the critical value needed to test the null hypothesis in this problem?

Assume that we conduct an experiment using a randomized block design to determine the influece of 4 different diets on the weights of bison.  We group the blson into 10 blocks, where the bison within each of the 10 blocks have similar weights.  The partially completed Analysis of Variance table is shown below. Source          df        SS                MS                F Total             39      15,919.2 Diet                3         3.298.7 Block              9       12,073.9 Error             27            546.6                                Calculate the mean squares for blocks.

Two fair coins are tossed and the events A and B are defined as follows: A: {At least one head appears} B: {Exactly one head appears} Find P (A)

Assume that the mean length of time required to complete the Columbus Marathon was 4.5 hours.  Further assume that the standard deviation of the times required to complete the race was 0.50 hours.  The winning time was 2.3 hours.  Calculate the z-score for the runner with the winning time of 2.3 hours.  Based on this z-score, is this time of 2.3 hours an outlier?  Why or why not?

Find the variance of a binomial probability distribution with a sample size of n = 25 and a probability of success of 0.30.

For a fixed confidence coefficient, the width of the confidence interval increases as the sample size increases.

Scientists want to estimate the difference in twinning rate of two lines of beef cattle that have been selected for increased frequency of twin births.  Last spring, 40 of the 100 cows in Line 1 gave birth to twins.  In Line 2, 30 of the 100 cows gave birth to twins. Construct a 90% confidence interval for the true difference in population proportions of cows giving birth to twins in Lines 1 and 2.  In the interest of time, you can assume that the sample sizes are large enough that it is appropriate to use a large-sample confidence interval.

The weights of 5 dogs (in pounds) are as follows: 10     20     25     30     40 Find    ΣXi2{“version”:”1.0″,”size”:{“width”:”45″,”height”:”52″,”auto”:true},”math”:”ΣXi2″}

Suppose that a random sample of 625 measurements is selected from a population with a mean µ = 500 lb and a variance σ2 = 100 lb2.  What is the mean and standard deviation of the sampling distribution of the sample mean?

A population of turkeys has a mean weight of 20 lb and a standard deviation of the weights equal to 4 lb.  A turkey breeder selects a large number of samples of 36 turkeys each, calculates the mean weight of the turkeys in each of these samples, and then graphs the sample means. Regardless of the shape of the distribution of the population of turkey weights, would we expect the sample means to be approximately normally distributed?