A four-character password to log onto a computer is drawn from the digits 0-9 and a subset of 23 letters of the alphabet (repetition is permitted). Determine the number of passwords possible if
a) the letters used are not case sensitive (that is, a lowercase letter is treated the same as an uppercase letter).
b) the letters used are case sensitive (that is, an uppercase letter is considered different than the same lowercase letter).

What is the measure of angle tvu shown in the diagram below

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?

Suppose you just purchased a digital music player and have put 8 tracks on it. after listening to them you decide that you like 4 of the songs. with the random feature on your player, each of the 8 songs is played once in random order. find the probability that among the first two songs played (a) you like both of them. would this be unusual? (b) you like neither of them. (c) you like exactly one of them. (d) redo () if a song can be replayed before all 8 songs are played.