# Math Help - Binomial Probability on graphing calculator

1. ## Binomial Probability on graphing calculator

These questions are to be done on a graphing calculator. The questions give n, p, x but I am having difficulty figuring out what is what.

1. In a history class, Colin and Diana both write a multiple choice quiz. There are 10 questions. Each question has five possible answers. What is the probability that:
a) Colin will pass the test if he guesses an answer to each question.
b) Diana will pass the test if she studies so that she has a 75% chance of answering each question correctly.

I really don't have a clue on how to approach these types of questions, any help would be really appreciated

thanks
~G

2. Originally Posted by the-G
These questions are to be done on a graphing calculator. The questions give n, p, x but I am having difficulty figuring out what is what.

1. In a history class, Colin and Diana both write a multiple choice quiz. There are 10 questions. Each question has five possible answers. What is the probability that:
a) Colin will pass the test if he guesses an answer to each question.
b) Diana will pass the test if she studies so that she has a 75% chance of answering each question correctly.

I really don't have a clue on how to approach these types of questions, any help would be really appreciated

thanks
~G
You must use the three-prong approach:

1. Define the random variable.

2. State the distribution the random variable follows.

3. Write down a probability statement of the problem.

a)
1. Let C be the random variable number of answers Colin gets correct.

2. C ~ Bin(n = 10, p = 1/5)

3. $Pr(C \geq 5) = ?$

Depending on the type of graphics calculator you have, you might need to re-write $Pr(C \geq 5)$ as $1 - Pr(C \leq 4)$

b)
is left for you.