Ateacher surveyed her class after they had taken a vocabulary test. eighteen of the students claimed they had studied at least one hour for the test. the remaining twelve students admitted that they had not studied for the test at all. the test results (expressed as a percent) for the two groups are shown below.

studied: 87, 100, 94, 79, 92, 100, 95, 83, 89, 99, 100, 91, 89, 95, 100, 93, 96, 83
did not study: 82, 72, 45, 91, 58, 83, 65, 87, 90, 77, 73, 89

part 1: calculate the mean of the group that studied, rounded to the nearest tenth.
part 2: calculate the mean absolute deviation of the group that studied, rounded to the nearest tenth.
part 3: how many of the scores (from the group that studied) are within one mean absolute deviation of the mean