SOLUTION: In a class of 40 people the probability of meeting a student of at least 13 years old is 0.8. Calculate the numbers of students in class who are expected to be less than 13 years

Question 985628: In a class of 40 people the probability of meeting a student of at least 13 years old is 0.8. Calculate the numbers of students in class who are expected to be less than 13 years
Answer by mathmate(429) (Show Source): You can put this solution on YOUR website!

Given:
A class of 40 students.
Probability of a student being >= years old = 0.8

Solution:
number of students, n = 40
probability of a student being not >=13 years old, p
= probability of a student being < 13 years old = 1-0.8 = 0.2
Expected value = np = 40 * 0.2 = 8

Answer: Eight students are expected to be under 13.
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