a utility company hires pollsters to knock on random doors in different parts of town to survey residents about the cost of their electric bill. would this study be biased? why or why not?

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?

Determine if the equation defines y as a function of x: 2xy = 1. yes o no

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25