Question

Can you guys teach me how to do this??

Answer 1

The usual margin of error we strive for is a 95% probability that our estimate is within the margin.   Assuming a normal distribution (and that we have a big enough sample not to worry about t tests) that corresponds to between minus and plus two standard deviations of the mean (remember the 68-95-99.7 rule).   So our margin of error is plus or minus two standard deviations.

Answer: ±2%