An important measurement in a textile industry is the tensile strength of a produced material. Suppose that the tensile strength (in pounds per square inch) of a roll of woven polypropylene is normally distributed with a mean of 89 and a standard deviation of 4.

i) What is the probability that the tensile strength will be somewhere between 80 and 100 pounds per square inch? [2 Marks]

ii) Find the probability that the tensile strength of the woven polypropylene is greater than 95 pounds per square inch. [1 Mark]

iii) Find the two values for tensile strength which give a middle area between the 80th percentile of the distribution.