Determine the mean and variance of the random variable with the following probability mass function. f(x) = (125/31)(1/5)^x x = 1,2,3

last question i !

Let f (x) = x e8x. find a formula for the nth derivative of f, where n is any positive integer. use x and n in your answer if needed. f (n)(x) =

Write two subtraction equations that are equivalent to 5 + 12 = 17.

Sarah took the advertising department from her company on a round trip to meet with a potential client. including sarah a total of 11 people took the trip. she was able to purchase coach tickets for $280 and first class tickets for $1280. she used her total budget for airfare for the trip, which was $6080. how many first class tickets did she buy? how many coach tickets did she buy?