Homework Help: statistic

Posted by tanya on Saturday, December 4, 2010 at 11:16pm.

Quiz has 6 questions. Each question has five possible answers,
only one of each 5 answers is correct.
If student randomly guesses on all six questions,
what is the probability to answer 2 questions right?

Tip: first, you have to define parameters of Binomial distribution:
n - how many trials/questions do you have
p - probability guessing right answer to each question
x - how many successes do you expect.
Then use Appendix Table or Excel function for Binomial distribution.
Answer

statistic - MathMate, Sunday, December 5, 2010 at 8:54am
Assuming the 6 questions are independent,
n=6 (questions)
p=probability of guessing the right answer (1/5)
x=exactly the number of successes over the 6 questions (2).

Look up the appendix table, or the Excel function to calculate the probability.

Alternatively, use the formula:
P(x) = C(n,x)*p^x*(1-p)^n-x
Where C(n,x) represents the number of combinations of taking n things, x at a time.
statistic - Mare, Tuesday, October 25, 2011 at 11:48am
.8
statistic - Anonymous, Wednesday, October 17, 2012 at 1:39pm
on a test midterm exam each multiple choice question provides five possible answers. what is the probability of randomly guessing three consecutive questions correctly?

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