Mrs. rodrigues wants to compare the spread of the test scores of her two biology classes. which statistic should she use? (multiple choice) a.) mean
b.) standard deviation
c.) median
d.) mode

if anybody can help me with this, thank you so much! i'm trying to pass a pre-test on e. d.g. e.n. u.i. t.y :( if you know the answer, please explain instead of just giving me the answer alone. thank you! <3

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?