1 SD= 68% of the population 2 SD= 95% of the population 1 SD= 99.7% of the population
They tell us the standard deviation is +/- 50 from the mean.
So women b/w ages 50-54 had a mean of 246. 1 SD= 196-296 meaning 68% of females in this range are between this range.
That means 32% are not within this range (100-68=32). They are either above OR below this range.
The question is asking how many will be above 296. So you divide 32 by 2 so that you get the percentage of only those falling above 296.
look at FA 2019 pg. 261
in a Gaussian, 66% are within 1 SD and 95% within 2 SD
this is high yield af
submitted by โm-ice(370)
This question only concerns women in the 50-54 age group. The group has a mean of 246 and standard deviation of 50. Therefore, all those with values greater than 296 are all those above one standard deviation. 2/3 of all values on a normal distribution are within one standard deviation in either direction. Therefore, 1/3 are outside of this in either direction, meaning 1/3 of women have a value less than 196 or greater than 296. If we split that in half to only choose those greater than 296, we get 1/6 women, which is about 16%.