Answer:
79 is the correct
Explanation:
he should consider surveying 79 app-based drivers to be 99% sure of knowing the mean salary within ±$0.71. The correct answer is 79.
To determine the sample size needed to estimate the mean with a given level of confidence, we can use the formula:
n = (Z * σ / E)^2
where:
n = sample size
Z = Z-score corresponding to the desired confidence level (99% confidence corresponds to Z = 2.576)
σ = standard deviation
E = margin of error
In this case, the margin of error is ±$0.71, so E = $0.71.
Substituting the given values into the formula:
n = (2.576 * 2.7 / 0.71)^2
n ≈ 79
Therefore, she should consider surveying 79 app-based drivers to be 99% sure of knowing the mean salary within ±$0.71. The correct answer is 79.
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