Then there are 20 people who made mistakes in 100× (1-80%) =1,and the number of people who made mistakes in questions 2, 3, 4 and 5 are10, 15, 22 and 23, in total.
Because it is stipulated that a person who has made more than three mistakes is not qualified.
Therefore, among the unqualified people, everyone just made three mistakes, with the largest number of unqualified people and the lowest pass rate.
That is, at most 90÷3=30 people are unqualified, that is, at least 70 people are qualified, and the pass rate is at least 70%.
What is the maximum throughput? Of course, it can't be treated as "assuming that each unqualified person just makes five mistakes, at least 90÷5= 18 people are unqualified, at most 82 people are qualified, and the qualified rate is at most 82%".
Because in the questions 1, 2, 3, 4 and 5, the number of people making mistakes is 20, 10, 15, 22 and 23 respectively.
Therefore, at most, there can only be 10 people with 5 questions all wrong,10 = 5 people with 4 questions all wrong, and 20- 15=5 people with 3 questions all wrong.
And 5× 10+4× 5+3× 5 = 85 < 90, that is, the number of unqualified people is at least 10+5+5=20.
Therefore, the maximum number of qualified people is 80, and the maximum pass rate is 80%.