# P-value

• May 28th 2010, 04:55 AM
IDontunderstand
P-value
On a summer day it says that the probability that a hot dog stand will sell out of hot dogs is 3/5
find at least 70 of 100 days the hotdogs are sold out

I used 1-Binomcdf(100, (3/5), 70) then this gives me an answer that is not a choice.
• May 28th 2010, 05:52 AM
mr fantastic
Quote:

Originally Posted by IDontunderstand
On a summer day it says that the probability that a hot dog stand will sell out of hot dogs is 3/5
find at least 70 of 100 days the hotdogs are sold out

I used 1-Binomcdf(100, (3/5), 70) then this gives me an answer that is not a choice.

At least means 70 or more.

X ~ Binomial(n = 100, p = 3/50 and your job is to calculate $\Pr(X \geq 70) = 1 - \Pr(X \leq {\color{red}69})$.
• May 29th 2010, 12:05 AM
matheagle
most likely you're expected to approximate this with a normal distribution with

$P(Normal >69.5)$
• May 29th 2010, 12:16 AM
mr fantastic
Quote:

Originally Posted by matheagle
most likely you're expected to approximate this with a normal distribution with

$P(Normal >69.5)$

Not this time. The Binomcdf command mentioned in the original post suggests using a TI graphics or CAS calculator here.
• May 29th 2010, 12:51 AM
matheagle
I don't own any of these calculators, so I had no idea what that meant.
The most scientific one I use is a TI-30.
I had a fancier one that did all these percentiles, but I gave that to a grad student last year as a graduation gift.
I just googled binomial calculator and came across
Binomial Probability Calculator
These can be found all over the net.