Let's calculate it then. Using this handy table
from an earlier posting, using the values from the "average" of the seven shot groups results expected accuracy of 1.81 ± .362" shooting from 7 yards and using a bench rest.
1. calculate mean of all groups (1.60 + 1.64 + 1.69 + 1.83 + 1.87 + 1.99 + 2.03 = 12.65 / 7 = 1.81")
Mean
2. subtract mean from each value, then square results sqrt(.21)(.17) (.12) .03 .06 .19 .22
3. sum the results and divide by number of values in the set 46 + .41 + .35 + .17 + .24 + .44 + .47 = 2.54 / 7 = 0.362"
expected variance
Then let's see how many standard deviations from the expected accuracy it is to hit a quarter sized target of 0.95"
So, (.95-1.81)/.362 = (2.357) deviations from mean. Consulting the
probability tables, that results in a 0.0091. So given a normal probability distribution curve, one would be expect to maintain a quarter sized group less than 1% of the time. Change the criteria to shooting freehand and at 50 yards and I'd say you'd go up a few more standard deviations.