# Bionomial Probability Distribution

1. Apr 2, 2004

### PARAJON

I need help on this problem.. my answer that i get is the following for A, but i'm not sure. can you help me with a and b. thank you...;.

In a binomial situation n=5 and pie = .40 Determine the probabilities of the following events using the binomial formula.

a. x = 1
n = 5

P (x) = nCx x (1 - ) n - x

P (1) = 5!
1! (5-1)! 1 (.40) 1 (1-.40) 5-1

120 (.40) 1 (.60) 4

b. x = 2
n =5

2. Apr 2, 2004

### matt grime

The probability of an event lies between 0 and 1. You've got 5 choose 1 as 5!1!, when it's 5, and the 1 and 4 should be powers you're raising 0.4 and 0.6 to.

If the probability of a success on trial is p (and q=1-p), then the probability of r successes in n trials is:

$$\binom{n}{r}p^rq^{n-r}$$

where

$$\binom{n}{r} = \frac{n!}{r!(n-r)!}$$

and is available as a button on your calculator