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# help

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Assume that when adults with smartphones are randomly​ selected, 61% use them in meetings or classes. If 8 adult smartphone users are randomly​ selected, find the probability that exactly 3 of them use their smartphones in meetings or classes

Feb 16, 2020

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Thanks for the A2A. I'm going to explain this very briefly.

61% is 61/100 in fraction form. Now, we can see the probability of just 1 case.

"find the probability that exactly 3 of them use their smartphones in meetings or classes". We can do $$\frac{61^3*39^5}{{100}^{8}}$$ and get approximately .002.

However, there are many cases so we will have to put in values for the combination formula.

After you substitute, you will get $$\frac{8!}{5!*3!}$$. That is a total of 56 cases.

Multiply .00204 and 56. The answer in decimal form is  .11424.

In percent form, it is 11.424%.

Cheers!

Feb 16, 2020