SOLUTION: In a lecture class of 100 students, 12 are left handed. If two students are chosen at random, what is the probability that: a) Both are left-handed b) Neither are left-handed

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Question 1200636: In a lecture class of 100 students, 12 are left handed. If two students are chosen at random, what is the probability that:
a) Both are left-handed
b) Neither are left-handed
c) Extend your probability tree diagram to show the possible outcomes if three students are chosen.
Answer by ikleyn(52874) About Me  (Show Source):
You can put this solution on YOUR website!
.


        Probably,  the shortest way to answer questions  (a)  and  (b)  is  THIS 


(a)  P = %2812%2F100%29%2A%2811%2F99%29 = %2812%2F100%29%2A%281%2F9%29 = %284%2F100%29%2A%281%2F3%29 = %281%2F25%29%2A%281%2F3%29 = 1%2F75 = 0.1333  (rounded).    ANSWER



(b)  P = %28%28100-12%29%2F100%29%2A%28%28100-13%29%2F99%29 = %2888%2F100%29%2A%2887%2F99%29 = %2888%2A87%29%2F%28100%2A99%29 = %288%2F9%29%2A%2887%2F100%29 = %282%2F9%29%2A%2887%2F25%29 = %282%2A87%29%2F%289%2A25%29 = 174%2F225 = 0.7733  (rounded).    ANSWER

Solved.

These formulas do not require explanations: they are SELF-EXPLANATORY and speak for themselves.