Suppose that the average birth weights of babies born at hospitals owned by a major health maintenance organization (HMO) are approximately normal with mean 6.75 pounds and standard deviation 0.54 pound. What proportion of babies born at these hospitals weigh between 6 and 7 pounds? Find the 95th percentile of these birth weights.

1. Name columns A and B of an Excel spreadsheet as “c,” and “P(x ,5c),” respectively.

Then enter the two values for c (6 and 7) in cells A2 and A3. Proceed as in Example 6.14, this time selecting Insert Function ➤ Statistical ➤NORM.DIST from the Formulas tab, and clicking OK. The Dialog box shown in Figure 6.22 will appear

2. Enter the location of first value of c (cell A2) into the first box, the appropriate mean and standard deviation in the second and third boxes, and the word TRUE into the fourth box. The resulting probability is marked as “Formula result50.08243327” at the bottom of the box, and when you click OK, the probability P(x #6) will appear in cell B2. To obtain the other probability, simply place your cursor in cell B2, grab the square handle in the lower right corner of the cell and drag the handle down to copy the formula into the other cell to obtain P(x #7)50.6783045.
3. Finally, use the values calculated by Excel to calculate

Transcribed Image Text:

Function Arguments NORMDIST Mean 675 Standard dev 54 Cumulative Te 675 t 0.54 t TRUE 008243327 x Returns the normal distribution for the specified mean and standard deviation Cumulative in a logical value for the cumulative distribution function, use TRUE for the probability density function FALSE Formula result 0.00243327 Hel 8 OK Cancel