How many text messages do twelfth grade students send on ave…
How many text messages do twelfth grade students send on average on a typical day? You think it is around 20 texts a day, but your friend thinks it is more than that. You decide to see if there is significant evidence that twelfth grade students send on average more than 20 texts a day. A random sample of 21 twelfth grade students is taken. The sample mean is 23.26 with a sample standard deviation of 12.68. A boxplot of the data does not have strong skewness or outliers. The hypotheses is as follows: H0: μ = 20 Ha: μ > 20 a. The test statistic is 1.18, what is the p-value? b. For this significance test, you fail to reject H0 and find no significant evidence that the true mean number of texts sent on a typical day by twelfth graders is greater than 20. What type of error could you have made? c. If instead you performed a significance test to see if the true mean number of texts sent a day was different than 20, what level of significance would the 90% confidence interval on the same set of data agree with?