In a certain commercial bank customers may withdraw cash through one of the 2 retailers at the counter one average one of the retailers take 3 minutes while the other takes 5 minutes to serve a customer . if the 2 start to serve the customer at the same time , find the shortest time it takes to serve 200 customers

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?