The Number Average Length of A and B Runs

The second definition we wish to introduce is the number average length of A (and B) runs. This is simply defined in Equation 6-37. 

If you think about it you will realize that the terms on the right hand side of Equation 6-40 simply add up to all the A s that are present, i.e., (Equation 6-41)  

And we end up with our expression for the number average length of A and (by analogy) B runs (Equations 6-42)  

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