SOLUTION: Richard has just been given a ten-question multiple choice test in his history class. Each question has five answers only one of which is correct. Since Richard has not been to c

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Question 863346: Richard has just been given a ten-question multiple choice test in his history class. Each question has five answers only one of which is correct. Since Richard has not been to class recently, he does not know any of the answers. Assume that Richard guesses randomly on all ten questions.
a. Find the probability he will answer all ten questions correctly.
b. Find the probablity he will answer five or more correctly
c. Find probability that the will answer none correctly.
d. Find probability that he will answer at least three questions correctly.
and if its possible please show me how to work it out to get the answer.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

 P = .2,  N = 10

Using TI Calculator for cumulative probabilities

a. Find the probability he will answer all ten questions correctly.(.2)^10

 b. Find the probability he will answer five or more correctly 1 - binomcdf(10,.2,4) = .0328

 c. Find probability that the will answer none correctly. (.8)^10

 d. Find probability that he will answer at least three questions correctly.

   1 - binomcdf(10,.2, 2)  =  .3222