Estimated Standard Error Question

[helpmeplease40]

For A, I am pretty sure that the formula you use is standard deviation divided by the square root of N but since there are 2 standard deviations I'm not sure what to do. Any help is appreciated

 

[BigBeachBanana]

For A, I am pretty sure that the formula you use is standard deviation divided by the square root of N but since there are 2 standard deviations.

That's the standard error for estimating the sample mean. There is more than one kind of standard error depending on your interest.