Question

The director of library services at a college did a survey of types of books (by subject) in the circulation library. Then she used library records to take a random sample of 888 books checked out last term and classified the books in the sample by subject. The results are shown below.

Subject Area	Percent of Books on Subject in Circulation Library on This Subject	Number of Books in Sample on This Subject
Business	32%	298
Humanities	25%	203
Natural Science	20%	215
Social Science	15%	101
All other subjects	8%	71

Using a 5% level of significance, test the claim that the subject distribution of books in the library fits the distribution of books checked out by students.

(a) What is the level of significance?


State the null and alternate hypotheses.

H₀: The distributions are different.
H₁: The distributions are different.H₀: The distributions are different.
H₁: The distributions are the same.    H₀: The distributions are the same.
H₁: The distributions are the same.H₀: The distributions are the same.
H₁: The distributions are different.

(b) Find the value of the chi-square statistic for the sample. (Round the expected frequencies to three decimal places. Round the test statistic to three decimal places.)


Are all the expected frequencies greater than 5?

YesNo    

What sampling distribution will you use?

Student's tchi-square    uniformbinomialnormal

What are the degrees of freedom?


(c) Estimate the P-value of the sample test statistic.

P-value > 0.1000.050 < P-value < 0.100    0.025 < P-value < 0.0500.010 < P-value < 0.0250.005 < P-value < 0.010P-value < 0.005

(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis of independence?

Since the P-value > α, we fail to reject the null hypothesis.Since the P-value > α, we reject the null hypothesis.    Since the P-value ≤ α, we reject the null hypothesis.Since the P-value ≤ α, we fail to reject the null hypothesis.

Answer 1

Category	pi	Observed Freq. (Oi)	Expected Freq. (Ei)	(Oi - Ei)^2/Ei
Business	0.32	298	284.16	0.674
Humanities	0.25	203	222	1.626
Natural Science	0.2	215	177.6	7.876
Social Science	0.15	101	133.2	7.784
All other subjects	0.08	71	71.04	0.000
		888		17.96

a)
alpha = 0.05

H0: The distributions are the same.
H1: The distributions are different.

b)
chi-square = 17.960

c)
p-value = 0.0013

P-value < 0.005

d)
Since the P-value ≤ α, we reject the null hypothesis.