You went to the store to get buy school supplies! You purchased binders, notebooks and pencils In total, the 47 items you bought cost $105 and you bought 3 times as many notebooks as you did
binders. A binder costs $3.50, a notebook costs $2.25, and a pencil costs $1.75. How many of each
item did you purchase?

In a test for esp (extrasensory perception), a subject is told that cards only the experimenter can see contain either a star, a circle, a wave, or a square. as the experimenter looks at each of 20 cards in turn, the subject names the shape on the card. a subject who is just guessing has probability 0.25 of guessing correctly on each card. a. the count of correct guesses in 20 cards has a binomial distribution. what are n and p? b. what is the mean number of correct guesses in 20 cards for subjects who are just guessing? c. what is the probability of exactly 5 correct guesses in 20 cards if a subject is just guessing?