Researchers examined the 1999-2000 National Health and Nutrition Examination Survey (NHANES) to estimate the dietary intake of 10 key ingredients by study participants. One of those nutrients was calcium, with intake measured in milligrams (mg). For adults 60 years or older, they found a mean daily intake of 721 mg with a standard deviation of 454 mg. Using these values for the mean μ and standard deviation σ for the U.S. population:
a. Compute the probability that a single randomly chosen adult over 60 years old will have a daily calcium intake of UNDER 400 mg
b. Compute the probability that a single randomly chosen adult over 60 years old will have a daily calcium intake of OVER 1000 mg