How does multiplying a vector by a scalar value of -pi change the vector?
a) the vector will change direction and increase in magnitude.
b) the vector will change direction and decrease in magnitude.
c) the vector will not change direction but will increase in magnitude.
d) the vector will not change direction but will decrease in magnitude.

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?