Phonics is an instructional method which children are taught to connect sounds with letters are groups of letters. A sample of 135 first graders Who were learning English for us to identify as many letter sounds as possible in a period of one minute. The average number of letters sounds identified was 34.04 with a standard deviation of 23.62.

Construct an 80% interval for the mean number of letters sounds identified in one minute round the answers to two decimal places.

an 80% confidence interval for the mean letter of sounds identified and one minute is [] < mean < []