stat theory says approximately 68% of measurements lie between +- one standard deviation. assume we have 100 students in our class. if in midterm 1 the mean score is 80 and standard deviation is 6, and you scored 86. approximately how many students scored below you?

Answer 1

since 86 is 1 std above the mean, that means that 34% are within 1 std above and below. That leaves 16% more than 1 std above or below the mean.

So, starting all the way out to the left, we have

16% more than 1 std below 80
68% within 1 std of 80
So, 84% scored below 86, or 84 students

Answer 2

How did you get 34% and 16%? Thanks

Answer 3

come on, man!
34% is 1/2 of 68%
34% above the mean, 34% below the mean.

Subtract the 68% from 100% leaves 32% outside 1 std.

16% way below the mean, 16% way above the mean.