SOLUTION: A multiple choice test has 100 questions. For subjects making random guesses for each answer, the mean number of correct answers is 20.0 and the standard deviation of the numbers o

Question 922803: A multiple choice test has 100 questions. For subjects making random guesses for each answer, the mean number of correct answers is 20.0 and the standard deviation of the numbers of correct answers is 4.0. For someone making random guesses for all answers, is it unusual to get 25 correct answers? Use statistics to justify your answer.
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
mean = 20.0 and the standard deviation = 4.0.

Z = 5.05/4 AND Z = 4.95/4
P(x = 25) = normalcdf(1.2375,1.2625) = .00457 using TI
0r
P(z ≤ 1.2625)- P(z ≤ 1.2375) = .8966- 8920 = .0046 using z-value
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