An educational psychologist wishes to know the mean number of words a third grader can read per minute. she wants to ensure that the estimate has an error of at most 0.3 words per minute. a previous study found that the mean was 25.8 words per minute. assuming that the standard deviation is 4.5 , what is the minimum number of third graders that must be included in a sample to construct the 98% confidence interval? round your answer up to the next integer.