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# IB Stats idk how to do this one - repost on my acc oops sorry

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1 how do I do this?

Feb 8, 2021

#1
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Have you been given a table?

Maybe like this one

Yours may be different presented differenly.

If 5.48% contain more, then   (100-5.48)% = 94.52% = 0.9452

Find 0.9452 in the body of the table.

I highlighted it, it is 1.60

So  14.5oz has a Z-score of 1.6

the average is 14.1 oz with a z-score of 0

0.4 oz =>  z-score of 1.6

0.4/1.6=0.25

So the mean of your distribution is 14.1 oz and the standard deviation is 0.25g

B)

14.1-13.9=0.2 grams below the mean.  0.2

13.9 grams is 0.2 grams below the mean

0.2/0.25=0.8

That is 0.8 of a standard deviation.

So the z score will be -0.8

the area below -0.8 is the same as the area above +0.8.

Which is also the same as 1- (the area below +0.8)

Which from the table is 1-0.7881 = 0.2119.

So 21.19% will be rejected.

Here is a simple little site where you can check your answers

http://davidmlane.com/hyperstat/z_table.html C very high.

Yes I know you are meant to do more than that.  But that is enough for me.