Answer:
C. 20
Step-by-step explanation:
The order in which the members are selected is important. The first one selected is the president and the second is the vice president.
So we use the permutations formula to solve this question.
Permutations formula:
The number of possible permutations of x elements from a set of n elements is given by the following formula:

In this problem:
2 people are going to be chosen from a set of 5. So

So the correct answer is:
C. 20
Okay, so let's find the actual failure rate first. 6/1000 times 100 (to give over a 100%) equals to 0.6. The actual failure rate is 0.6%. The theoretical probability is 0.2% 0.6-0.2=0.4. The difference is 0.4%.
Hope that helped!
It isn't easy really but you can always divide the number out. For example 50% of 200 is 100 by dividing 200 by 2 or 25% of 100 is 25 by dividing 100 by 4 since 25% is equivalent to 1/4