19. The Mental Development Index (MDI) of the Bayley Scales of Infant Development is a standardized measure used in longitudinal follow-up of high-risk infants. It has approxi- mately a normal distribution with a mean of 100 and a standard deviation of 16.

a) What proportion of children have a MDI of at least 120?

b) What proportion of children have a MDI of at least 80?

c) Find the MDI score that is the 90th percentile

d) Find the MDI score such that 10% of the population have MDI scores below that value.

e) Find and interpret the lower quarule, inedian, and upper quartile of MDI

f) Find the interquartile range of MDI scores, and, using the definition of outlier in terms of the IQR, find the ranges of MDI scores that would be considered outliers