Idont under stand this explain answers .

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).

Anyone know? will mark brainliest if correct!

The owner of the plant nursery where you were tells you to fill 350 ml bottles from a 30 l from a fertilizer