Robert has 11 red folders, 6 blue folders, 15 green folders, and 7 black folders on his shelf.
If he randomly grabs a folder, what is the probability that it will be either blue or green?

A.6/13

B.7/13

C.23/38

D.3/5

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Polygon hh is a scaled copy of polygon gg using a scale factor of 1/4. polygon h's area is what fraction of polygon g's area?

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x