Evaluate the radical expression. Express your answer as an integer, simplified fraction, or a decimal rounded to two decimal places. If the expression does not represent a real number, indicate not a real number. ​

Answer this question, only if you know the answer. 30 points and brainliest!

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).

How many $20 bills do you need to have to make $280