We choose a number from the set {10,11,12,...,99} uniformly at random. (a) Let X be the first digit and Y the second digit of the chosen number. Show that X and Y are independent random variables. (b) Let X be the first digit of the chosen number and Z the sum of the two digits. Show that X and Z are not independent.

Which of the statements about the graph of the function y = 2x are true? check all of the boxes that apply. the domain is all real numbers x because the exponent of 2 can be any real number when the x-values increases by 1 unit, the y-value multiplies by 2. the y-intercept is (0, 1). the graph never goes below the x-axis because powers of 2 are never negative. the range is all real numbers.