Question

How many problems did I get incorrect on a test if I have 15 questions and got 67% correct

Answer 1

Well, it depends. If some questions are worth five points and some are worth ten, we'd need more information.

If all of the questions are worth the same, then we have enough information.

So, would you like to assume that all questions are worth the same number of points?

Answer 2

yes, lets assume its one point per question

Answer 3

Okay!

So, first we have to think about what that percentage actually means!

It is the number right, divided by the total number, times 100%.
Why? Well, you want to know how correct you are, overall. So you compare what you knew to what there was to know. It will usually be a decimal, so you look at the percentage because it looks nicer.

So
percentage = numberCorrect / total

Have you had algebra yet?

Answer 4

Sorry,

percentage = numberCorrect / total * 100%

Answer 5

If you know algebra, you can make these to be all variable. Like

p = n / t * 100%
Then you can find the number you got right. The rest, then, are wrong.

Answer 6

Algebraically...
numberWrong + numberCorrect = total
So
numberWrong = total - numberCorrect
Or something like
w = t - n

If you know about substitution, you can build one big formula to start off! But it's more complicated and takes a little practice.

Answer 7

if im correct i think the number you got wrong would be 5. because 67% of 15 ~ 10.05, so im pretty sure the number wrong is 5.

Answer 8

Looks good to me!