1. The diameter of red blood cells in healthy adults is approximately normally distributed with mean 7.5 microns and standard deviation 0.3 microns.
a. What fraction of red blood cells have diameter between 7.1 and 7.6 microns?
b. Find the 80th percentile of the diameter of red blood cells.
2. Of all the trees planted last year by a landscaping firm, 10% died within a month. Suppose a new landscaping firm is hired to plant 15 new trees. Let X denote the number of trees planted (out of 15) that died.
a. What values of X suggest that the new landscaping company has a lower failure rate?
b. What values of X are consistent with the previous landscaping company's failure rate?
c. What values of X indicate that the new landscaping company has a higher failure rate than the previous contractor?