distribution percentiles

Question

suppose that the distribution of scores on an exam is closely described by a normal cure with mean 100. the 16th percentile of this distribution is 80. what is the 84th percentile?

Answer 1

The normal curve has the properties that it is symmetric about the mean, and that the mean is equal to the median (which is the 50th percentile value).  Because of the symmetry about the 50th percentile, the 84th percentile will be the same distance away from the mean as the 16th percentile, just in the opposite direction.