Want this question answered?
A normal distribution with a mean of 65 and a standard deviation of 2.5 would have 95% of the population being between 60 and 70, i.e. +/- two standard deviations.
95 percent of measurements are less than 2 standard deviations away from the mean, assuming a normal distribution.
if standard deviation is 4 minutes 95% probability is about 2 standard deviations (actually 1.96) so you would need to allow 30 + 8 = 38 minutes
About 98% of the population.
15/1000
A normal distribution with a mean of 65 and a standard deviation of 2.5 would have 95% of the population being between 60 and 70, i.e. +/- two standard deviations.
2.576 sd
in a normal distribution, the mean plus or minus one standard deviation covers 68.2% of the data. If you use two standard deviations, then you will cover approx. 95.5%, and three will earn you 99.7% coverage
95% is within 2 standard deviations of the mean.
By the definition of standard deviation, 95.46% of the normal population will be within 2 SD of the mean. Explanation: The normal distribution of a population means it follows the "bell curve". The center of this bell curve is the population's mean value. One standard deviation defines two areas (on the left and right side of the central "mean" value) under the bell curve that each have 34.13% of the population. The next standard deviation adds two additional areas under the curve, each having 13.6% of the population. Adding the areas under the curves on both sides gives us (34.13% + 13.6%) x 2 = 95.46%
95 percent of measurements are less than 2 standard deviations away from the mean, assuming a normal distribution.
Percent variation is the standard deviation divided by the average
if standard deviation is 4 minutes 95% probability is about 2 standard deviations (actually 1.96) so you would need to allow 30 + 8 = 38 minutes
The answer will depend on what the distribution is. Non-statisticians often assum that the variable that they are interested in follows the Standard Normal distribution. This assumption must be justified. If that is the case then the answer is 81.9%
About 98% of the population.
Never!
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?