Re: Is this binomial distribution?


t...@xxxxxxxxxxxx wrote:
> Here's a big hint: Go to Excel and look up the help function for
> "Negative Binomial Distribution."

LOL! Why go to Excel, arguably the worst spread*** for probability
and statistical computations, to learn simple PROBABILITY concepts?

Carmen asked,

*> Assume that a certain random event occurs one time in ten (these are

*> independent events).

*> c) What is the probability of succeeding at least once in 10 tries?
In
*> 20 tries? How many successes do we expect in 10 tries? 20 tries?

Why is a NEGATIVE binomial distribution needed to answer it?

It's a simple binomial problem with p = 1/10.

1- (1-p)^10 = 1 - (.9)^10

and 1 - (.9)^20 for the first parts, and the expected number of
successes are np which is 1 and 2 respectively for n= 10 and 20.

Furthermore, the numerical precision in Excel leaves much to be
desired.

BTW, the prob of at least one success in 20 trials is approximately
..878423345409431, to 15-significant figures.

-- Bob.

.

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