Question: Referring to #14, The following iron intakes, in milligrams, were obtained during a 24-hour period for 45 randomly selected adult females under 51:

15.0 18.1 14.4 14.6 10.9 18.1 18.2 18.3 15.0

16.0 12.6 16.6 20.7 19.8 11.6 12.8 15.6 11.0

15.3 9.4 19.5 18.3 14.5 16.6 11.5 16.4 12.5

14.6 11.9 12.5 18.6 13.1 12.1 10.7 17.3 12.4

17.0 6.3 16.8 12.5 16.3 14.7 12.7 16.3 11.5

At the 1% signficance level, do the data suggest that adult females under 51, on average, are getting less than the RDA of 18 mg of iron? Assume that the population standard deviation is 4.2 mg (Note \(\bar{X}\) = 14.68 mg.)