At a university, the average cost of books per student has been $400 per student per semester. the dean of students believes that the costs are increasing and that the average is now greater than $400. he surveys a sample of 40 students and finds that for the most recent semester their average cost was $430 with a standard deviation of $80. what is the test value for this hypothesis test? test value:

1. why is a frequency distribution useful? it allows researchers to see the "shape" of the data. it tells researchers how often the mean occurs in a set of data. it can visually identify the mean. it ignores outliers. 2. the is defined by its mean and standard deviation alone. normal distribution frequency distribution median distribution marginal distribution 3. approximately % of the data in a given sample falls within three standard deviations of the mean if it is normally distributed. 95 68 34 99 4. a data set is said to be if the mean of the data is greater than the median of the data. normally distributed frequency distributed right-skewed left-skewed