Question 1191056
z=(x-mean)/sd
so a is asking what percent are more than 1 sd less than the mean.  This is 16%, since 32% probability is more than 1 sd from the mean in both directions, and we only want half of that.
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The middle 95% of jumps are within + and - 2 sd s of the mean
This is 66 inches from the low end (90-2*12) and 114 inches from the top end (90+2*12)