1. ## Hypothesis Test Question

A multiple-choice quiz contains ten questions. For each questions there are one correct answer and four incorrect answers. A student gets three correct answers on the quiz. Test the hypothesis that the student is guessing.

2. Originally Posted by flaming
A multiple-choice quiz contains ten questions. For each questions there are one correct answer and four incorrect answers. A student gets three correct answers on the quiz. Test the hypothesis that the student is guessing.
I don't know. But I guess it's kinda helpful knowing what the probability is.

=> $\begin{pmatrix} 10 \\ 3 \end{pmatrix}$

5 choices per question;
probability for guessing the right answer is therefor $\frac{1}{5} = 0.2;$
probability for guessing the wrong answer is therefor $\frac{4}{5} = 0.8.$

=> probability("three right answers") = $\begin{pmatrix} 10 \\ 3 \end{pmatrix}*0.2^3*0.8^7 \approx 0.20$

the probability of guessing exactly 3 correct answers out of 10 is 20% (=0.2)

3. Originally Posted by Rapha
I don't know. But I guess it's kinda helpful knowing what the probability is.

=> $\begin{pmatrix} 10 \\ 3 \end{pmatrix}$

5 choices per question;
probability for guessing the right answer is therefor $\frac{1}{5} = 0.2;$
probability for guessing the wrong answer is therefor $\frac{4}{5} = 0.8.$

=> probability("three right answers") = $\begin{pmatrix} 10 \\ 3 \end{pmatrix}*0.2^3*0.8^7 \approx 0.20$

the probability of guessing exactly 3 correct answers out of 10 is 20% (=0.2)
Since the null hypothesis is student is guessing I think you'll actually need to calculate $\Pr(X \leq 3)$.