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John tossed a fair coin 3 times. What is the probability that the outcome was “tails” exactly twice?

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Re: John tossed a fair coin 3 times. What is the probability that the outcome was “tails” exactly twice?

by Scott@TargetTestPrep » Wed Mar 08, 2023 11:42 am
BTGmoderatorDC wrote: ↑
Tue Feb 21, 2023 5:18 pm
 John tossed a fair coin 3 times. What is the probability that the outcome was “tails” exactly twice?

A. 1/8
B. 1/4
C. 3/8
D. 1/2
E. 9/10


OA C

Source: EMPOWERgmat
We need to determine the following:

P(TTH) = (1/2)^3 = 1/8

Since TTH can be arranged in 3!/2! = 3 ways, the probability is 3 x (1/8) = 3/8.

Answer: C

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