The National Association of Landscape Professionals has determined that on average mulch lasts 87 days befor fading or degrading. Due to an improved production process that extends the life of mulch, the Association believes that there has been an increase in the useful life of standard pine bark mulch. A sample of 36 yards of mulch showed an average life of 88.5 days before it began to fade. Assume from past information that it is known that the standard deviation of the population is 9 days.
a. Give the null and the alternative hypotheses.
b. Compute the test statistic.
c. At 99% confidence using the critical value approach, test management's belief.
d. What is the p-value associated with the sample results? What is your conclusion based on the p-value?