Perfume is sold in two different sizes of bottle
the 80ml bottle is priced at £55
the 50ml bottle is usually priced at £45, but is on special offer. If you buy one 50ml bottle of perfume, you can get a second half price.
by calculating the price per ml, determine which offers the best value for money, the 80ml bottle or two 50ml bottles?

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?