Original scores :
45,65,70,80,85,100
IQR = 85 - 65 = 20
new scores :
65,70,80,85
IQR = (80 + 85)/2 - (65 + 70)/2 = 82.5 - 67.5 = 15
You would probably need a little larger sample of people because not all people wear corrective lenses. In almost any other survey, this would be a scientist’s dream, but in this one, you’d need it to be a little bigger.
3 divided by 64 is 0.046875