Probability for Difference in Proportions
The table below summarizes data from two independent random samples of customers. Which of the following correctly computes the probability that the difference in sample proportions (revamped minus unrevamped) is greater than 0.10?
| Restaurant | Sample Size (n) | Sample Proportion (p̂) |
|---|---|---|
| Revamped | 110 | 0.25 |
| Unrevamped | 120 | 0.19 |
A
Apply an unwarranted continuity correction leading to a probability calculation around 0.5, which misapplies normal approximation techniques.
B
Reverse the difference in the numerator to compute , which incorrectly yields a negative z-score and an incorrect probability.
C
Assume a negligible standard error, concluding erroneously that the probability is 0.
D
First, compute the standard error as . Then, find the z-score , so that .
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