Use the accompanying table of standard scores and their percentiles under the normal distribution to find the approximate standard score of the following data values. Then state the approximate number of standard deviations that the value lies above or below the mean.

a. A data value in the 60th percentile
b. A data value in the 80th percentile
c. A data value in the 54th percentile

a. The standard score for the 60th percentile is approximately
nothing.
​(Round to two decimal places as​ needed.)