Alls to the line of a large computer distributor follow a poisson distribution with a mean of 20 calls per minute. determine the following: (a) mean time until the one-hundredth call (b) mean time between call numbers 50 and 80 (c) probability that three or more calls occur within 15 seconds

i dont know what you want me to answer for this but im guessing 2: 11?

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."

y - 25 = 2 ( x - 10 ) should be the answer