# Thread: probability

1. ## probability

The time taken by a randomly selected applicant for a mortgage to fill out a certain form has a normal distribution with mean value $\displaystyle 10$ min and a standard deviation $\displaystyle 2$ min. If five individuals fill out a form on one day and six on another, what is the probability that the sample average amount of time taken on each day is at most $\displaystyle 11$ minutes?

So is this just $\displaystyle P \left(z \leq \frac{1}{2/\sqrt{5}} \right) = \Phi(1.118) = 0.8686$ and $\displaystyle P \left(z \leq \frac{1}{2/\sqrt{6}} \right) = \Phi(0.816) = 0.7939$?

2. I get 0.8682 for the first one.

On the second you have the wrong value for $\displaystyle \frac{\sqrt{6}}{2}$

,

### time taken by a randomly selected applicant for a mortgage to fill out a certain form has a normal distribution with mean value 9 min and standard deviation 4 min. if five individuals fill out a form on one day and six on another, what is the probability

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