For the answer to the question above, it is just simple and easy. I will the answers directly and the answer is Sara hiked 2 more miles this week than last week.
She got a total of 16 items correct. You can find this out by turning this into a percentage question. She got 4/5 of the items correct. 4/5 = 0.8, 0.8 = 80% 80% * 20 = 16.
Since there are 2 possibilities for each bat (hit or out), the amount of total possibilities is 2 * 2 * 2 = 8. There is only one possibility out of those eight that gives us three hits, therefore the probability is 1 / 8 or 0.125.