sound it out

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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.