The pH measurements of water specimens from various locations along a given river basin are Normally distributed, with standard deviation σ= 0.3. The average pH of water specimens from 4 randomly selected locations on this river basin is x̄= 7.8. A 95% confidence interval for μ was computed for these data. If, instead of 4 water specimens, we had measured the pH of 16 water specimens, how would the margin of error of a 95% confidence interval for μ compare to the original 95% confidence interval based on a sample of 4 specimens?

Question

Quizplus · Accepted Answer

The margin of error decreases with the square root of the sample size. Increasing the sample size from 4 to 16 quadruples the sample size, so the margin of error would be halved.

The PH Measurements of Water Specimens from Various Locations Along