A university laboratory is tasked with reporting the average nitrate concentration in campus drinking fountains. The 95 % 95\% confidence intervals for the mean nitrate concentration are currently too wide for administrative comfort. Assuming the variance in nitrate levels cannot be changed, what should the laboratory do to obtain narrower confidence intervals?

Increase the number of samples taken from the fountains.

Use a lower-quality testing method.

Report the median instead of the mean.

Increase the confidence level to 99 % 99\% .

A university laboratory is tasked with reporting the average nitr...

Confidence Intervals for Population Mean: Videos & Practice Problems