SOLUTION: A student takes a 20-question, multiple-choice quiz with 5 choices for each question, find the probability of guessing at least 15 correct out of the 20. Would you consider this ev

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Question 168719This question is from textbook elementary statistics
: A student takes a 20-question, multiple-choice quiz with 5 choices for each question, find the probability of guessing at least 15 correct out of the 20. Would you consider this event likely or unlikely to occur? This question is from textbook elementary statistics

Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!
A student takes a 20-question, multiple-choice quiz with 5 choices for each question, find the probability of guessing at least 15 correct out of the 20. Would you consider this event likely or unlikely to occur?

On your TI-83 or TI-84 calculator, type in

1-binomcdf(20,1/5,14)

and press ENTER.

You'll see 1.802764E-7 which means

matrix%281%2C3%2C1.802764%2C+%22%D7%22%2C+10%5E%28-7%29%29

or 0.0000001802764

which is about 1 chance in 5.5 million.

So it's extremely unlikely.

Edwin