Finding the binomial probabilities of:
n=11. p=.5, P(x8)
So do I find P(x=0)+P(x=1)...+P(x=7) in the binomial probability formula?

Question

Finding the binomial probabilities of:
n=11. p=.5, P(x>8)
So do I find P(x=0)+P(x=1)...+P(x=7) in the binomial probability formula?

aum · Answer

But that would be finding P(x < 8).  They want P(x > 8).

anonymous · Answer

So do I find 8 -11?

aum · Answer

P(x=9) + P(x=10) + P(x=11)

anonymous · Answer

little confusing but thank you

aum · Answer

If you prefer you can find  P(x=0)+P(x=1)...+P(x=7) and then calculate 1 - the sum of probabilities.

anonymous · Answer

Thank you for the help...I had P(x=0)+...P(x=7) all figured but i erased, and i wished i would have thought that.

loser66 · Answer

what does p =0.5 mean?

anonymous · Answer

P is probability of success or failures in the binomial

loser66 · Answer

and what is the probability of mass function? f(x) =?

loser66 · Answer

oh, you mean the probability of failure or success is 1/2.

anonymous · Answer

yep

aum · Answer

With P(x=0)+P(x=1)...+P(x=7) you have to calculate 8 probabilities and add then up and then subtract the sum from 1.
But the easier method would be P(x=9) + P(x=10) + P(x=11) where you calculate 3 probabilities and add them up.