SOLUTION: A parent- teacher committee consisting of 4 people is to be formed from 20 parents and 5 teachers. Find the probability that the committee will consist of these people. (assume th

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Question 351398: A parent- teacher committee consisting of 4 people is to be formed from 20 parents and 5 teachers. Find the probability that the committee will consist of these people. (assume that the selection will be random).
a. all teachers
b. 2 teachers and 2 parents
c. all parents
d. 1 teacher and 3 parents
Answer by solver91311(24713) About Me  (Show Source):
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The probability of successes in trials where the probability of success is is given by:



where is the number of combinations of things taken at a time and is computed using

There are 25 people to choose from, 20 parents and 5 teachers, so the probability of picking a teacher on any given trial is .

For your first part you want to calculate:



For the second part:



For the third part:



For the fourth part:



Calculation hints: and


John

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