Phonics is an instructional method in which children are taught to connect sounds with letters or groups of letters. a sample of 134 first-graders who were learning english were asked to identify as many letter sounds as possible in a period of one minute. the average number of letter sounds identified was 34.06 with a standard deviation of 23.83.
(a) construct a 98% confidence interval for the mean number of letter sounds identified in one minute.
(b) if a 95% confidence interval were constructed with these data, would it be wider or narrower than the interval constructed in part a? explain.
(c) if a sample of 150 students had been studied, would you expect the confidence interval to be wider or narrower than the interval constructed in part (a) ?