I am not sure if this is correct, but here's my reasoning based on statistics: avg IQ is 100, and under a normalized bell curve that would include 95% of the population, so to move 3 std dev above or below would be:
1 std dev includes: 100-95 = 5. 5/2 = 2.5 so 2.5 + 95 => 97.5%
2 std dev includes: 100 - 97.5 = 2.5. 2.5/2 = 1.25 so 97.5 + 1.25 = 98.75
3 std dev includes: 100 - 98.75 = 1.25. 1.25/2 = .625 so 98.75 + .625 = 99.375
100 - 99.375 is percentage of population who are geniuses (more than 3 std dev above the mean) - about 0.6%, which is more than 1 in 200 people - That seems like a lot but unfortunately I'm not one of them :)
How many standard deviations is 16.50 from the mean?
You can't average means with standard deviations. What are you trying to do with the two sets of data?
That depends on what the standard deviation is.
49
It is mean + 2*standard deviation.
All minor deviations occurring with two standard deviations under the Gaussian curve are considered normal. Deviations occurring outside of two standard deviations are considered abnormal.
I'm assuming "genius" means an unusual value (more than two standard deviations) in the right tail. This is (100 - 95.45)/2 = 2.275 percent, approximately. So: 6,575,000,000 * 0.02275 = 149,581,250 geniuses ... not that special, huh?
How many standard deviations is 16.50 from the mean?
2.576 sd
The sum of standard deviations from the mean is the error.
95% is within 2 standard deviations of the mean.
The mean for the WISC, like the WAIS, is 100. The deviations from 100, or standard deviations, are 15.
2 times the standard deviation!
You can't average means with standard deviations. What are you trying to do with the two sets of data?
standard deviations
That depends on what the standard deviation is.
Z-Score tells how many standard deviations a measurement is away from the mean.