High School

Suppose the mean high school football score per game in the United States is 49.5 points with a standard deviation of 4.8 points. Jesse thinks the mean high school football score per game in Ohio is more than 49.5 points. He randomly surveys 40 coaches in Ohio and finds the mean high school football score per game is 51.7 points. Jesse uses software to test the hypothesis that high schools in Ohio score higher than 49.5 points per game. The output of his test is shown, where the z-statistic is calculated as 2.899 standard deviations above the mean.

Test of [tex]\mu = 49.5[/tex] vs [tex]\mu > 49.5[/tex]
The assumed standard deviation = 4.8
N Mean SE Mean Z
40 51.7 0.759 2.899

Determine the lower and upper limit for the P-value to four decimal places.

Answer :

To calculate the P-value limits based on the z-statistic of 2.899 in a one-tailed test, we use the normal distribution table. The lower limit for the P-value is 0.0019, which corresponds to the given z-statistic, and the upper limit is 0.9981, which represents the probability of finding a value greater than the z-score under the normal curve.

The question involves conducting a hypothesis test on the mean high school football score per game in Ohio based on a z-statistic given as 2.899. Since the z-statistic is 2.899 standard deviations above the mean, we are dealing with a one-tailed test (because the hypothesis is that Ohio scores higher, not just different).

To determine the lower and upper limit for the P-value, we need to refer to the standard normal distribution table. A z-score of 2.899 corresponds to a P-value that is the area under the normal curve to the right of the z-score. Unfortunately, standard z-tables typically only give the area to the left. However, since the normal distribution is symmetrical, finding the area to the left for a z-score of -2.899 gives the same numerical value for the area to the right of +2.899.

Consulting a z-table or using statistical software, we can find that the area to the left of -2.899 is approximately 0.0019. Therefore, the P-value for our one-tailed test is the area to the right, which is 1 - 0.0019, or 0.9981. The lower limit for the P-value is the P-value itself (since it cannot be lower), which is 0.0019, and the upper limit is the chance of an observation falling above this z-score in the upper tail, which is 0.9981.