SOLUTION: A multiple-choice test has 10 questions each of which has 4 possible answers, only one of which is correct. If Judy, who forgot to study for the test, guesses on all questions, wha

Algebra ->  Probability-and-statistics -> SOLUTION: A multiple-choice test has 10 questions each of which has 4 possible answers, only one of which is correct. If Judy, who forgot to study for the test, guesses on all questions, wha      Log On


   

Question 1150526: A multiple-choice test has 10 questions each of which has 4 possible answers, only one of which is correct. If Judy, who forgot to study for the test, guesses on all questions, what is the probability that she will answer exactly 3 questions correctly?
Answer by ikleyn(52919) About Me  (Show Source):
You can put this solution on YOUR website!
.

    P = C%5B10%5D%5E3%2A%281%2F4%29%5E3%2A%283%2F4%29%5E%2810-3%29 = %28%2810%2A9%2A8%29%2F%281%2A2%2A3%29%29%2A%281%2F4%29%5E3%2A%283%2F4%29%5E7 = 0.2502823.    ANSWER