Probability question

G

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I need help with this one...

It's found that the number of defective parts produced per day by a certain production line are normally distributed with a mean f 4 and a standard deviation of 2.

Find the probability that

a) More than 3 defective parts are produced on a given day.
b) Between 2 and 5 defective parts are produced on a given day?

thanks
 
normal344zn.gif



z=xμσ\displaystyle z=\frac{x-\mu}{\sigma}

z=342=12\displaystyle z=\frac{3-4}{2}=\frac{-1}{2}

P(z>12)\displaystyle P(z>\frac{-1}{2}).

Look them up in the Standard Normal Distribution table.

Subtract from 1.

Do the same for part b.

z=242\displaystyle z=\frac{2-4}{2} and z=542\displaystyle z=\frac{5-4}{2}

P(1<z<1/2)\displaystyle P(-1<z<1/2)

Subtract the 2 results.
 
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