Posted by Anonymous on .
The director of an innercity hospital believes that the average cost per gunshot injury of patients admitted to the hospital’s emergency room is $18,000. A random sample of 9 gunshot injuries had a mean of $17,213 with a standard deviation of $572. Calculate the standardized test statistic and determine whether or not the conclusion of the test refutes the director’s claim. Assume the population is normally distributed and use a significance level of 5%.

statistics 
MathGuru,
Try a onesample ttest to determine your test statistic. Once you have the test statistic, compare the test value to the critical value from a ttable using degrees of freedom along with the significance level. If the test statistic exceeds the critical value from the table, reject the null. If the test statistic does not exceed the critical value from the table, do not reject the null.
I hope this will help get you started.