VSabina wants to subtract 451 – 98 mentally. First Sabina adds 2 to 98 to get 100.
What should Sabina’s next step be? What is the difference?
A.

Add 9 to 451. The difference is 360.
B.

Subtract 2 from 451. The difference is 349.
C.

Add 2 to 451. The difference is 353.
D.

Subtract 100 from 451. The difference is 351.

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?