As part of its freshman orientation process, a college gives a math placement exam to incoming freshmen. The math department is interested in whether there is a statistically significant difference in the average exam score for students in different programs, at a level of α=0.01. The exam scores for random samples of science, engineering, humanities, and business majors are shown in the following table. The math department has confirmed that the samples were randomly selected and independent, that the populations are normally distributed, and that the population variances of scores are equal. Use a TI-83, TI-83 plus, or TI-84 calculator and the following table of critical values for the F-distribution to calculate the degrees of freedom, critical value, and test statistic for the data set, rounding the test statistic to two decimal places.
Critical Values of the F-Distribution for α=0.01
Degrees of Freedom for the Numerator | |||||
Degrees of Freedom for the Denominator |
1 | 2 | 3 | 4 | 5 |
30 | 7.56 | 5.39 | 4.51 | 4.02 | 3.70 |
31 | 7.53 | 5.36 | 4.48 | 3.99 | 3.67 |
32 | 7.50 | 5.34 | 4.46 | 3.97 | 3.65 |
33 | 7.47 | 5.31 | 4.44 | 3.95 | 3.63 |
34 | 7.44 | 5.29 | 4.42 | 3.93 | 3.61 |
35 | 7.42 | 5.27 | 4.40 | 3.91 | 3.59 |
36 | 7.40 | 5.25 | 4.38 | 3.89 | 3.57 |
37 | 7.37 | 5.23 | 4.36 | 3.87 | 3.56 |
38 | 7.35 | 5.21 | 4.34 | 3.86 | 3.54 |
39 | 7.33 | 5.19 | 4.33 | 3.84 | 3.53 |
40 | 7.31 | 5.18 | 4.31 | 3.83 | 3.51 |
Science |
Engineering |
Humanities |
Business |
87 |
88 |
85 |
82 |
79 |
89 |
84 |
78 |
84 |
88 |
91 |
80 |
83 |
86 |
84 |
78 |
89 |
89 |
83 |
78 |
87 |
87 |
79 |
79 |
91 |
94 |
91 |
74 |
83 |
90 |
81 |
79 |
85 |
86 |
82 |
83 |
86 |
86 |
91 |
79 |
Provide your answer below:
Numerator degrees of freedom = , denominator degrees of freedom = , critical value = , test statistic =
using excel>data>data analysis>one way anova
we have
Anova: Single Factor | ||||||
SUMMARY | ||||||
Groups | Count | Sum | Average | Variance | ||
Science | 10 | 854 | 85.4 | 11.6 | ||
Engineering | 10 | 883 | 88.3 | 6.011111 | ||
Humanities | 10 | 851 | 85.1 | 19.43333 | ||
Business | 10 | 790 | 79 | 6 | ||
ANOVA | ||||||
Source of Variation | SS | df | MS | F | P-value | F crit |
Between Groups | 458.5 | 3 | 152.8333 | 14.20237 | 2.89E-06 | 4.377 |
Within Groups | 387.4 | 36 | 10.76111 | |||
Total | 845.9 | 39 |
Numerator degrees of freedom =3
, denominator degrees of freedom = 36
, critical value =4.38
, test statistic =14.20
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