Birth weights at a local hospital have a Normal distribution with a mean of 110 oz. and a standard deviation of 15 oz. a) Find the proportion of infants with birth weights above 125 oz. Explain. b) Find the proportion of infants with birth weights between 125 oz. and 140 oz. Explain.
I'm not sure how to do this. If anyone has a detailed explanation and answer, that would be great.
Hint: You probably learned the fractional area under the normal distribution for $\pm1\sigma, \pm2\sigma, \pm3\sigma$ from the mean as $0.6827, 0.9545,$ and $0.9973$, respectively. (Or roughly, $68\%, 95\%,$ and $99.7\%$.)
If you're looking at just one side of the normal distribution, the percentages are half this.
So for each part, express the interval in terms of standard deviations from the mean. The numbers are really nice in this problem.
Can you take it from here?