Quiz revision? How to improve ?

Question

How would you improve the quizzes revision?
I just found a question in a challenge with duplicated answer...and I wondered why do SoloLearn allows this xD

Answer 1

means taking java challenges can be bad this time
//i think most of the quizzes are approved & have many possible errors
//if i find , i will post screenshot

Answer 2

double sum = 0;
for(int i=1; i<=10; i++){
sum += 1/i;
}
System.out.print(sum);
Answers:
1.0
10
1.0
10.0
I didn't know how to post a quiz xD

Answer 3

Thank you :D