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# S2- normal distribution difference tables

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1. Hey guys

Basically,I just want to know HOW the difference tables work. Let me give an example:

My Z value came to 0.3846, and so did the mark scheme's. Then, when I went to the tables, I looked at 0.38, which is 0.6480, and added the value at 5 as i thought 0.0046 should be rounded. That gave an overall value of 0.6499.

The mark scheme, however, had the same result as me (0.3846) for Z, yet had 0.6497- there isnt even a 17 value in the differences table!
2. If you want to use it for one more decimal place you add it for example 0.8000 and then in the differences table you find the third decimal for instance 3 follow it down to the value in line with the first decimal and add it like so. IIf it is 15 then you get 0.8015. however i want to know what to do if you need another decimal place after that I have been looking at the mark schemes and they require more accuracy.
Anyone able to help me out?

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