Mean = 48
65-95-99.7 rule tells us:
65% of the data falls within 1 st. dev of the mean (both sides equally)
95% of the data falls within 2 st. dev of the mean (both sides equally)
99.7% of the data falls within 3 st. dev of the mean (both sides equally)
We want to find between 33 and 48.
48 is the mean, so we need to find within one side (left) of the mean.
48 - 33 = 15 (that is 3 standard deviation, 5 + 5 + 5 = 15)
This is basically 1 side of the curve.
3 standard deviation means 99.7%, but since this is HALF of that total, we have:
99.7%/2 = 49.85%
Note:
