SOLUTION: Assume that when adults with smartphones are randomly​ selected, 61% use them in meetings or classes. If 9 adult smartphone users are randomly​ selected, find the proba
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Question 1099328: Assume that when adults with smartphones are randomly selected, 61% use them in meetings or classes. If 9 adult smartphone users are randomly selected, find the probability that exactly 5 of them use their smartphones in meetings or classes.
The probability is
nothing.
You can put this solution on YOUR website! 9 total are selected.
5 use smartphones
The rest of the selection, or 4 do not
Probability that 5 use smartphones while the other four do not is:
The result of the multiplication is your answer.
Be wary of answers from tutor Lightning Fast. He often misreads the question; and his answers are incorrect far too often.
In his answer to this question, he used the factor (0.61) 6 times instead of 5. That I suppose is forgivable....
But his answer is incomplete. Taken literally, the calculation he shows is only the probability that the first five (not six) people use their smartphones in meetings or classes and the last 4 do not.
The calculation needs to include the number of different ways that 5 of the 9 people use their smartphones in meetings or classes.
The correct probability calculation is
where C(9,5) is "9 choose 5", the number of ways of choosing 5 of 9 things.
