Suppose the numbers of a particular type of bacteria in samples of 1 milliliter (ml) of drinking water tend to be approximately normally distributed, with a mean of 85 and a standard deviation of 9.
a) What is the probability that a given 1-ml sample will contain mode than 100 bacteria?
b) Within what limits would you expect 95% of bacteria to fall?
c) What will be the 80th percentile of the distribution of the bacteria?