The article “Irritated by Spam? Get Ready for Spit” (USA Today, November 10, 2004) predicts that “ spit,” spam that is delivered via Internet phone lines and cell phones, will be a growing problem as more people turn to web-based phone services. In a poll of 5,500 cell phone users, 20% indicated that they had received commercial messages and ads on their cell phones. These data were used to test H0: p = 0.13 versus Ha: p > 0.13 where 0.13 was the proportion reported for the previous year. The null hypothesis was rejected.
a. Based on the hypothesis test, what can you conclude about the proportion of cell phone users who received commercial messages and ads on their cell phones in the year the poll was conducted?
b. Is it reasonable to say that the data provide strong support for the alternative hypothesis?
c. Is it reasonable to say that the data provide strong evidence against the null hypothesis?