An Internet report on a 1999 Gallup poll (https://www.gallup.com/poll/index.asp, August 2, 1999) included the following statement:
For results based on this sample, one can say with 95 percent confidence that the maximum error attributable to sampling and other random effects is plus or minus 3 percentage points."
What is the margin of error for this survey? Give two separate ways in which you know this is the answer.