6 wrong gives a score of 80%, 80% wrong means 6 correct.
78.38%
Nine.
30
The score would be 56%
The question does not specify what z is so this answer could be completely wrong. However, if the question is in the context of the standard Gaussian distribution, the answer is 0.493613 (to 6 dp)
90%.
Your answer is in your question unless your question is wrong.
78.38%
92 %
83.33%
You can get 60 questions wrong and get a 70 percent but if you get 61 wrong you are at a 69.5 percent.
Each question is worth 2.5 percent. You can get 8 wrong.
Well, darling, to get an 80 percent on a 70-question test, you can afford to get 14 questions wrong. As long as you nail the rest of those questions, you'll be golden. Just remember, it's not about how many you get wrong, it's about how many you get right.
80%
Nine.
30
20