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**107**about Goodness of fit test for a normal distribution.Question is about analysis of fat content of hambergers.

I understand that we need to have the two intervals

**-infinity< x< 26**and

**40< x<infinity**to find the class probabilities of intervals

26< x <28 and

38< x<40.

But why should the

**expected frequencie**s of the two intervals -infinity< x< 26 and 40< x<infinity be also calculated and

**used for chi Squared value**?

These two categories are

**not**there in the given data set.

Is it necessary to break our intervals such that they start from -infinity and end from infinity as this is a normal distribution?