Steps:
1. First, divide 82 by 100, since this is what you would have originally gotten with the ratio.
82 ÷ 100 = 0.82
2. Then multiply it by 50 (since this is how many questions were on the test)
0.82 × 50 = 41 <----- (the number of questions answered correctly)
3. Now that you have the two numbers you need, you can assemble the ratio.
Answer: 41/50
Hope I Helped! <3