40 points

a teacher 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: 88, 100, 94, 79, 92, 100, 95, 83, 89, 99, 100, 91, 89, 95, 100, 93, 96, 84
did not study: 82, 72, 45, 91, 58, 83, 65, 87, 90, 77, 73, 89

which of the following statements are true?

the mean of the group that studied is over 15 percentage points higher than the mean of the group that did not study.
there is no mode of the group that studied.
the median of the group that did not study is less than 80.
the median of the group that studied is over 95.
in general, those students that studied scored much higher than those students that did not study.