# Suppose x is a discrete, binomial random variable

1. Oct 20, 2006

### nachelle

How do I do this p(x<1) this sign has a _ under the <
n=6 p=0.1

Suppose x is a discrete, binomial random variable.

Calculate P(x > 2), given trails n = 8, success probability p = 0.3

[Hint: P(x > value) = 1 – P(x <= value) <= is a < with a _ under it

(tell me the number value you get)

2. Oct 20, 2006

A binomial random variable distribution is given by $$f(x)=\left( \begin{array}{c} n \\ x \end{array} \right) p^x (1-p)^{n-x}$$. That's a starting point.

Edit: one more hint - the probability that a discrete random variable will have a value less or equal x is $$F(x) = P(X \leq x) = \sum_{i;x_{i}\leq x}f(x_{i})$$.

Last edited: Oct 20, 2006
3. Oct 20, 2006

Staff Emeritus
Use the \le construction in tex. Remove the blanks in the tags here to get it.
[ tex]p(x \le 1)[/tex ]
to get
$$p(x \le 1)$$

4. Oct 20, 2006

### nachelle

Thank you for your help with how to make the symbols.... I also need help with the answers

5. Oct 20, 2006

$$P(x > 2) = 1 - P(x \leq 2)$$
$$P(x \leq 2) = \left( \begin{array}{c} 8 \\ 0 \end{array} \right) 0.3^0 (1-0.3)^{8-0} + \cdots$$ (sum until x = 2, including that case)