SOLUTION: We believe that 90% of the population of all Calculus I students consider calculus an exciting subject. Suppose we randomly and independently selected 21 students from the populat

Question 364104: We believe that 90% of the population of all Calculus I students consider calculus an exciting subject. Suppose we randomly and independently selected 21 students from the population. If the true percentage is really 90%, find the probability of observing 20 or more of the students who consider calculus to be an exciting subject in our sample of 21.
Found 2 solutions by amoresroy, robertb:
Answer by amoresroy(361) (Show Source): You can put this solution on YOUR website!
Probability of observing 20 or more students

= .90 * 21 / 20
= .945
= 94.5%
Note; 36% answer is too low. I don't know how 36% answer was solved.

Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
0.90 = probability that a student finds calculus exciting.
THEN...0.10 = probability that a student finds calculus not exciting.
This is a binomial experiment with p = 0.90 and n = 21. Therefore the probability of observing 20 or more of the students who consider calculus to be an exciting subject in our sample of 21 is given by:
, to 5 decimal places.
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