There are a couple of errors, that I could spot, but I just woke up so my math might also be wrong hahaha.
(0.25)(0.25)=0.0625, you have a 6.25% of getting a 100.
Correct
The other option to get a 50 is (0.25)(0.75)=0.1875, 18.75%.
Almost, that’s only true if the first one is the one you get right, but you can also get the second one right (3/4 * 1/4), meaning that it’s double your answer, or 37.5% chance of getting at least one right.
So there is a 75% chance of failing both.~
56.25% as per above
~If you get a second chance and can remember your two wrong answers, each problem now has only three options. To get each right, (0.33)(0.33)=0.1089, 10.89% chance.
That assumes you got both wrong the first time around.
To get one right, (0.33)(0.67)=0.2211, 22.11% chance. 67% chance of failing both a second time.~
Same as above, also same as getting the second one right.