(2 points) let u = {1,2,3,4,5,6}. determine x({2,3,5}) even integer and an odd integer is odd 12. (10 points) give a direct proof that the sum of an 13. (10 points) give an indirect proof that if n3 is even, then n is even. 14. (10 points) give a proof by contradiction that if 3n 2 is odd, then n is odd m |n] m and n, we have mn 15. (10 points) give a proof by cases that for any integers

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