Marisushi
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The length of an instant message conversation is normally distributed with a mean of 5 minutes and a standard deviation of 0.7 minutes.

What is the probability that a conversation lasts longer than 6 minutes?

All work explained please I really want to understand how to do this.

Respuesta :

This is called normal distribution. First we must find Z, to get z we do (X=6 here), (x-mean)/s.dev. so 6-5/0.7. This get 1.428. Now we use our table to get the probability of Z happening. This number is 0.9236. However this gives us the probability of P(Z{6). We want P(Z}6) so we do 1-0.9236, which gets us 0.0764.

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