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Assume that the average reaction time of drivers is normally distributed with average of 1.1 s and a standard deviation of 0.3 s.

  1. Compute the probability that in the selected simple random sample of 50 drivers we compute sample average, that is less than 1 s.

  2. Assess the proportion of drivers who have a longer reaction time than 1.25 s.

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    If you know that a bunch of $n$ random variables are normally distributed with mean $\mu$ and standard deviation $\sigma$, then the sample average is also normally distributed, with mean $\mu$ and standard deviation $\sigma/\sqrt{n}$. Do you know how to get the quantiles of a normal distribution?2012-05-22
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    Chris gave you the key to this and Andre made it explicit. It looks like a homework problem. Does Mathematics require homework problems to be labelled as such? At CrossValidate we do and we only give hints to homework rather than complete solutions.2012-05-22
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    Wasn't a homework realy... im studying for an exam and came across this problem and coulnd't solve it. Thus Andre's solution was very welcome.2012-05-22

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