Final answer:
The minimum number of times the safe should be audited per day is 2.
Step-by-step explanation:
The minimum number of times that the safe should be audited per day can be determined using probability calculations. Given that the probability of finding an accident caused by employee failure to follow instructions is p = .35, we can use the inverse of this probability to find the average number of reports the safety engineer would expect to look at until finding such an accident.
The probability of finding an accident in one audit is 1 - p = 1 - 0.35 = 0.65. The average number of reports until finding an accident can be calculated as 1 divided by this probability, which is 1/0.65 = 1.54.
Therefore, the minimum number of times that the safe should be audited per day is 2 times, as the safety engineer would need to look at a minimum of 2 reports before finding an accident cause by employee failure to follow instructions.