The data below represents the number of students in 10 7th grade classes.
20, 18, 21, 18, 22, 24, 18, 23, 23, 24

a. What is the median of the data:

b. What number of students describe the first quartile (mean of lower quartile):

c. What number of students describe the third quartile (mean of upper quartile):

d. What number of students describe the interquartile range (third quartile - first quartile):

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?