the height of 14 year old boys in the u.s. is normally distributed with a mean of 64.5 and a standard deviation of 3.1 in what is the normal curve by entering the value of each standard deviation
I think you're missing the rest of the question, but you can use the standard deviation and a normal curve to determine the likelihood that they'll fall into particular ranges. I've included some below for you.
61.4-67.6 - 68.37% likely to fall within this range. 58.3-70.7 - 95.45% likely to fall within this range. 55.2-73.8 - 99.73% likely to fall within this range.
