PLEASE HELP I DONT KNOW HOW TO EXPLAIN IT

Determine the mean and variance of the random variable with the following probability mass function. f(x)=( 729divided by 91) (1 divided by 9) superscript x baseline comma x equals 1,2,3 round your answers to three decimal places (e.g. 98.765).

Its due ! write an equation in which the quadratic expression 2x^2-2x 12 equals 0. show the expression in factored form and explain what your solutions mean for the equation. show your work.

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?