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- September 21st 2006, 06:55 AM #1

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- Aug 2006
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## mean and sd

Hiya...

I'm unsure where to start with this question...

The weights of cans of pears produced by a local canning factory are normally distributed with a mean of 500 grams and a standard deviation of 25 grams. Calculate the percentage of cans that weigh:

a. 430 grams or less.

b. between 525 and 550 grams.

Thanks!

- September 21st 2006, 07:24 AM #2

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- September 27th 2006, 07:21 AM #3

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correct me if i'm wrong but i think you can do this with the Texas Instruments Ti-83 calc.

for question A)

if you go 2nd->DISTR (above VARS) -> 2: normalCdf (-1*10^99, 430, 500, 25)

it will give you roughly 0.0026 which is 0.256% of cans will be 430 grams or less.

Its a very small number, but dont forget its almost 3 std. dev's off the mean.

if it were 3 std. dev's off the mean it would have a probability of (1 - 0.997)/2 = 0.0015 = 0.15%.

Hope this helps