I have attached a binomial question in excel (question & solution).

In part (e), the question asks for the P(between 5 and 15 inclusive)

The answer in cell B22 is:

0.9577 =BINOMDIST(15,B3,B4,1)-BINOMDIST(4,B3,B4,1)

Could you please explain why the solution refers to BINOMDIST(4,B3,B4,1) and not BINOMDIST(5,B3,B4,1)? i.e. why 4, not 5?

Thanks,

--Peter