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How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters? We want 98% confidence that the sample mean is within 4 minutes of the population mean, and the population standard deviation is known to be 12 minutes. 25 35 49 60

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MathPhys

Answer:

49

Step-by-step explanation:

Margin of error = critical value × standard error

ME = CV × SE

The critical value at 98% confidence is z = 2.326.

Standard error is SE = σ / √n.

4 = 2.326 × 12 / √n

n = 49

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