FOR A POPULATION WITH STANDARD DEVIATION=20: A. HOW LARGE A SAMPLE WOULD BE NEEDED TO OBTAIN A STANDARD ERROR LESS THAN 10 POINTS? B. HOW LARGE A SAMPLE WOULD NEEDED TO HAVE A STANDARD ERROR SMALLER THAN 5 POINTS? C. IF YOU WANTED YOUR SAMPLE MEAN TO BE WITHIN ONE POINT OS THE POPULATIONS MEAN (ON THE AVERAGE) HOW LARGE A SAMPLE WOULD YOU USE? Solution B. HOW LARGE A SAMPLE WOULD NEEDED TO HAVE A STANDARD ERROR SMALLER THAN 5 POINTS? s/n >5 --> 20/n > 5 --> 20/5 >n --> 4 > n --> n=4^2=16.