SOLUTION: If you guess at random on each question of a true-false test with 12 questions, what is the probability that you will get exactly 8 answers correct? Write your answer as a fractio

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Question 989839: If you guess at random on each question of a true-false test with 12 questions, what is the probability that you will get exactly 8 answers correct? Write your answer as a fraction or rounded to four decimal places.
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


The probability of exactly successes in trials where the probability of success on any individual trial is is given by:



You want 8 successes on 12 trials at

Plug in the numbers and do the arithmetic. If the notation is unfamiliar, it means the number of combinations of things taken at a time and is calculated by

If you have Excel (or Numbers on a Mac) 
=BINOMDIST(8,12,0.5,FALSE)
will save you some arithmetic.

John

My calculator said it, I believe it, that settles it