Posted by **Matt Borchelt** on Tuesday, December 13, 2011 at 9:50pm.

a 10 question multiple choice test has 4 possible answer for each question. A student selects at least 6 correct answers.

Find probability of this event:

(multiple choice)

A) .118

B) .995

C) .068

D) .571

- Math -
**bobpursley**, Tuesday, December 13, 2011 at 10:00pm
he got 6 right, 4 wrong. The question has no answer. Did he randomly guess, or did he know the answers to only six?

If he knew the answers to six, the probability is 1 that he gets those six.

If he knows 5, the prob is 1 he gets those right, plus pr =4(1/4)(3/4) he gets one more or a pr of .75 he gets six right knowing 5, guessing on the last four.

Well, we need to know how many he knew, I think.

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