Question

Answers to Multiple-Choice Problems: A student wants to see if the correct answers to multiple choice problems are evenly distributed. She heard a rumor that if you don't know the answer, you should always pick C . In a sample of 100 multiple-choice questions from prior tests and quizzes, the distribution of correct answers are given in the table below. In all of these questions, there were four options {A, B, C, D}.

Correct Answers (n = 100)

	A	B	C	D
Count	12	23	29	36

The Test: Test the claim that correct answers for all multiple-choice questions are not evenly distributed. Test this claim at the 0.05 significance level.

(a) The table below is used to calculate the test statistic. Complete the missing cells.
Round your answers to the same number of decimal places as other entries for that column.

	Correct	Observed	Assumed	Expected
i	Answer	Frequency (Oi)	Probability (pi)	Frequency Ei	(Oi − Ei)2 Ei
1	A		0.25	25.0	6.760
2	B	23		25.0	0.160
3	C	29	0.25		0.640
4	D	36	0.25	25.0
Σ		n = 100			χ2 =

(b) What is the value for the degrees of freedom?  
(c) What is the critical value of

χ²

? Use the answer found in the

χ²

-table or round to 3 decimal places.
t_α =  

(d) What is the conclusion regarding the null hypothesis?

reject H₀

fail to reject H₀    

(e) Choose the appropriate concluding statement.

We have proven that correct answers for all multiple choice questions are evenly distributed.

The data supports the claim that correct answers for all multiple choice questions are not evenly distributed.    

There is not enough data to support the claim that correct answers for all multiple choice questions are not evenly distributed.

Answer 1

(a)

The missing cells in the Table are completed as follows:

	Correct	Observed	Assumed	Expected
	Answer	Frequency (Oi)	Probability (pi)	Frequency (Ei)
1	A	12	0.25	25.0	6.760
2	B	23	0.25	25.0	0.160
3	C	29	0.25	25.0	0.640
4	D	36	0.25	25.0	4.84
		n = 100	1.00	100	= 12.40

(b)

Degrees of freedom = 4 - 1 = 3

(c)

= 0.05

From Table, critical value of = 7.8147

(d)

Since calculated value of = 12.40 is greater than critical value of = 7.8147:

Correct option:

reject H0.

(e)

correct option:

The data supports the claim that correct answers for allmultiple choice questions are not evenly distributed.