Question: how to calculate percentage from normal distribution?
Answer: Consider the normal distribution N(100, 10). To find the percentage of data below 105.3, that is P(x < 105.3), standartize first: P(x < 105.3) = P ( z < 105.3 − 100 10 ) = P(z < 0.53). Then find the proportion corresponding to 0.53 in Table A: look for the intersection of the row labeled 0.5 and the column labeled .