# Homework Help: Probability - Random Variables

1. Mar 7, 2012

### tjackson

1. The problem statement, all variables and given/known data

1. A test consists of 10 true-false questions.
(a) In how many ways can it be completed? (HINT: The task of completing the test consists
of 10 stages. Use the Product Rule.)

(b) A student answers the questions by
flipping a coin. Let X denote the number of correctly
answered questions.
(i) The distribution of X is:

binomial
hypergeometric
negative binomial
Poisson

(ii) Find the probability he/she will answer correctly at most 5 of the questions.

2. Relevant equations / Attempt at a solution

a) i believe this is just 210?

b.) i.) is this binomial??

ii.) $\stackrel{n}{k}$ * pk * (1-p)(n-k)

p = 1/2
k = 5
n = 10

$\stackrel{n}{k}$
is n choose k

2. Mar 7, 2012

### FileDeleted

a)correct
b)binomial
binomcdf(10,.5,5)

It's been awhile since I took statistics. There is a chance I'm wrong.

3. Mar 7, 2012

### Ray Vickson

Your answers are correct.

RGV

4. Mar 8, 2012

### tjackson

So these statements are correct?

p = 1/2
k = 5
n = 10

I apologize, I am not familiar with the 'binomcdf(10,.5,5)' format

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