1. The mean number of imperfections in the weave of a certain textile is of four per square yard. a) Find the probability that a 3-square-yard sample will contain at least one imperfection. (6p) b) The cost of repairing the imperfections in the weave is $10 per imperfection. Find the mean and standard deviation of the repair costs for an 8-square-yard bolt of the textile in question. (9p) c) If a random sample of size 10 such that each of which is one square-yard, find the probability that at least 3 of them have no imperfection. (10p)