Mary lou has 2 more nickels than pennies, and she has 30 coins all together. use x for the number of pennies.
a) 2(x + 2) = 30
b) x + (x + 2) = 30
c) 2x + 30 = 5
d) x + 2 = 30

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?