In: Statistics and Probability
A manufacturer of colored candies states that 13% of the candies in a bag should be brown,14% yellow,13% red, 24% blue, 20% orange, and 16% green. A student randomly selected a bag of colored candies. He counted the number of candies of each color and obtained the results shown in the table. Test whether the bag of colored candies follows the distribution stated above at the alpha equalsα=0.05 level of significance
Color | Frequency | Claimed Proportion |
Brown | 60 | 0.13 |
Yellow | 67 | 0.14 |
Red | 52 | 0.13 |
Blue | 60 | 0.24 |
Orange | 78 | 0.20 |
Green | 66 | 0.16 |
Determine the null and alternative hypotheses. Choose the correct answer below.
A.H0:The distribution of colors is not the same as stated by the manufacturer.
H1:The distribution of colors is the same as stated by the manufacturer.
B.H0:The distribution of colors is the same as stated by the manufacturer.
H1:The distribution of colors is not the same as stated by the manufacturer.
C.None of these.
Compute the expected counts for each color.
Color |
Frequency |
Expected Count |
|
Brown |
60 ? |
||
Yellow |
67 ? |
||
Red |
52 ? |
||
Blue |
60 ? |
||
Orange |
78 ? |
||
Green |
66 ? |
chi Subscript 0 Superscript 2=? |
What is the P-value of the test?
P-value=?
Based on the results, do the colors follow the same distribution as stated in the problem?
A.Do not reject Upper H 0. There is not sufficient evidence that the distribution of colors is not the same as stated by the manufacturer.
B.Do not reject Upper H 0. There is sufficient evidence that the distribution of colors is not the same as stated by the manufacturer.
C.Reject Upper H 0. There is not sufficient evidence that the distribution of colors is not the same as stated by the manufacturer.
D.Reject Upper H 0. There is sufficient evidence that the distribution of colors is not the same as stated by the manufacturer.
Solution:
Given:
Color | Frequency | Claimed Proportion |
---|---|---|
Brown | 60 | 0.13 |
Yellow | 67 | 0.14 |
Red | 52 | 0.13 |
Blue | 60 | 0.24 |
Orange | 78 | 0.20 |
Green | 66 | 0.16 |
Part a) Determine the null and alternative hypotheses.
B. H0:The distribution of colors is the same as stated by the manufacturer.
H1:The distribution of colors is not the same as stated by the manufacturer.
Part b) Compute the expected counts for each color.
Multiply each claimed proportion by N = 383.
Thus we get:
Color | Frequency | Expected Count |
---|---|---|
Brown | 60 | 49.79 |
Yellow | 67 | 53.62 |
Red | 52 | 49.79 |
Blue | 60 | 91.92 |
Orange | 78 | 76.60 |
Green | 66 | 61.28 |
Part c) Find
Chi square test statistic for goodness of fit
Where
Oi = Observed Counts
Ei =Expected Counts
Thus we need to make following table:
Color | Oi: Observed Frequency | Ei: Expected Count | Oi2/Ei |
---|---|---|---|
Brown | 60 | 49.79 | 72.304 |
Yellow | 67 | 53.62 | 83.719 |
Red | 52 | 49.79 | 54.308 |
Blue | 60 | 91.92 | 39.164 |
Orange | 78 | 76.60 | 79.426 |
Green | 66 | 61.28 | 71.084 |
383 |
Thus
Part d) What is the P-value of the test?
Use following Excel command:
=CHISQ.DIST.RT( X2 , df )
where
df = k - 1 = 6 - 1 = 5
=CHISQ.DIST.RT(17.004,5)
=0.004492
=0.0045
Thus P-value = 0.0045
Part e) Based on the results, do the colors follow the same distribution as stated in the problem?
Since P-value = 0.0045 < α = 0.05 level of significance, we reject the null hypothesis H0.
Thus correct answer is:
D.Reject H0. There is sufficient evidence that the distribution of colors is not the same as stated by the manufacturer.