A recent newspaper article reported the results of a survey of well-educated suburban parents. The responses to one question indicated that by age 2, children were watching an average of μ = 60 minutes of television each day. Assuming that the distribution of television-watching times is normal with a standard deviation of σ = 20 minutes, find each of the following proportions.

a. What proportion of 2-year-old children watch more than 90 minutes of television each day?

b. What proportion of 2-year-old children watch less than 20 minutes a day?