(4) An experiment is repeated in a civil engineering laboratory. The outcomes of these experiments are considered independent, and the probability of an experiment being successful is 0.7. I.What is the probability that no more than 6 attempts are necessary to produce 3 successful experiments? II.What is the average number of failures before 3 successful experiments occur? III.Suppose one needs 3 consecutive successful experiments. What is the prob- ability that exactly 6 attempts are necessary?