math
posted by PLEASE HELP .
The masses of newborn children are normally distributed with a mean of 3.4 kg and a standard deviation of 0.8 kg. A newborn is at risk if the baby'd mass falls in the lowest 4%. These babies have a mass of less than ____?

2.0 kg, which is 1.75 standard deviations below the mean.
Try using http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html
as a graphical aid