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A high school offers math placement exams for incoming freshmen to place students into the appropriate math class during their freshman year. three different middle schools were sampled and the following pass/fail results were found. run a test for independence at the 0.10 level of significance.

school a school b school c
pass 40 33 50
fail 59 45 67

After running an independence test, can it be concluded that pass/fail rates are dependent on school?
A. Yes, it can be concluded that pass/fail rates are dependent on school because the p-value = 0.9373.
B. Yes, it can be concluded that pass/fail rates are dependent on school because the p-value = 0.0627.
C. No, it cannot be concluded that pass/fail rates are dependent on school because the p-value = 0.9373.
D. No, it cannot be concluded that pass/fail rates are dependent on school because the p-value = 0.0627.

User Imm
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1 Answer

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A chi-square test of independence was performed to determine whether the pass/fail rates are dependent on school. The p-value was 0.9373, so we cannot conclude that the pass/fail rates are dependent on school correct option is c.

The chi-square statistic is calculated as follows:

χ² = Σ (O - E)² / E

where O is the observed number of students in each category, and E is the expected number of students in each category. The expected number of students in each category is calculated under the assumption of independence.

The degrees of freedom for the chi-square test of independence are (r - 1)(c - 1), where r is the number of rows in the contingency table and c is the number of columns. In this case, r = 2 and c = 3, so the degrees of freedom are (2 - 1)(3 - 1) = 2.

The p-value for the chi-square test is the probability of obtaining a chi-square statistic as large as or larger than the observed chi-square statistic, assuming that the null hypothesis is true. The p-value can be calculated using a chi-square distribution table or software.

The following table shows the expected number of students in each category, under the assumption of independence:

| School | Pass | Fail |

| A | 41.42 | 57.58 |

| B | 32.63 | 45.37 |

| C | 48.95 | 68.05 |

The chi-square statistic is calculated as follows:

χ² = (40 - 41.42)² / 41.42 + (33 - 32.63)² / 32.63 + (50 - 48.95)² / 48.95 + (59 - 57.58)² / 57.58 + (45 - 45.37)² / 45.37 + (67 - 68.05)² / 68.05 = 0.1294

The p-value for the chi-square test is 0.9373.

Since the p-value is greater than 0.10, we do not reject the null hypothesis. Therefore, we cannot conclude that the pass/fail rates are dependent on school.

The correct answer is C. No, it cannot be concluded that pass/fail rates are dependent on school because the p-value = 0.9373.

User Tymel
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