Posted by **Liz** on Tuesday, May 7, 2013 at 5:34pm.

You have a ten question multiple choice test in your next class and you did not study at all. Each question has four choices and only one correct answer. You are going to guess on each question. What is the probability that you score at least a 20% on the test.

- Statistics -
**MathMate**, Tuesday, May 7, 2013 at 8:38pm
Use binomial probability because:

probability is known and does not change over the experiment,

outcome is binomial (success or failure),

each step of the experiment is similar,

p=0.25

n=10

P(r)=number of question correct

=nCr(p^r)(1-p)^(n-r)

nCr = binomial coefficient = n!/((n-r)!r!)

P(0)=0.0563 (zero question correct)

P(1)=0.1877 (1 question correct)

Therefore, to get at least 20%, or 2 or more questions correct, we have

P(2+)=1-(P(0)+P(1))

=0.7560

## Answer This Question

## Related Questions

- English for john browm - Let me give you something on "multiple-choice" items ...
- Statistics - On a very short quiz, there is one multiple choice question with 5 ...
- Statistics - A 10 question test is all multiple choice. Each question has four ...
- Statistical concept 68-95-99.7 - 1. A student taking a midterm exam in Ancient ...
- Stat HW for. - 1. A student taking a midterm exam in Ancient History comes to ...
- Statistics - A student guesses blindly on a 20-question multiple choice test. If...
- Math - A multiple choice quiz contains five question. Each question has four ...
- math - You randomly guess the answers to two questions on a multiple-choice ...
- Math - Given a multiple choice test with 4 choices for each question and 17 ...
- statistics - A test consists of 12 multiple choice questions with 5 choices for...

More Related Questions