The International Bottled Water Association says that Americans on the average drink 4.6 (8-oz.) servings of water a day. Assume that the number of 8-oz. servings of water is approximately normally distributed with a standard deviation of 1.4 servings. (Give your answers correct to four decimal places.)

Question

The International Bottled Water Association says that Americans on the average drink 4.6 (8-oz.) servings of water a day. Assume that the number of 8-oz. servings of water is approximately normally distributed with a standard deviation of 1.4 servings. (Give your answers correct to four decimal places.) 
 (b) What proportion of Americans drink less than half the recommended 8 servings?

PsyDAG · Answer

"less than half" = less than 2.3

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.

Tom7 · Answer

z=(8-2.3)/1.4=4.07 graph 0.99998 is this the right way and how do you change the graph numbers since they are all 9's that would need to be rounding?

Sue 620 · Answer

I worked it and got a different answer for the graph number 0.9893 and tom worked and got something totally different, what are we doing wrong, trying to work together on some of these?