A sample of concrete specimens of a certain type is selected, and the compressive strength of each specimen is determined. The mean and standard deviation are calculated as x 5 3000 and s 5 500, and the sample histogram is found to be well approximated by a normal curve.
a. Approximately what percentage of the sample observations are between 2500 and 3500?
b. Approximately what percentage of sample observations are outside the interval from 2000 to 4000?
c. What can be said about the approximate percentage of observations between 2000 and 2500?
d. Why would you not use Chebyshev’s Rule to answer the questions posed in Parts (a)–(c)?