A student missed 8 questions on an English test and received a grade of 64%. If all the problems were of equal value, how many problems were on the test? Round off your answer to the nearest integer.

Question

A student missed 8 questions on an English test and received a grade of 64%.  If all the problems were of equal value, how many problems were on the test?  Round off your answer to the nearest integer.

anonymous · Answer

0.64x=8;x=8/0.64=...?

anonymous · Answer

13?

anonymous · Answer

Roughly, yes. But do you understand?

anonymous · Answer

No.  How did you know to divide by 0.64?

anonymous · Answer

Alright, the student got 64% of his test questions, right? Therefore, the product of 0.64 and the total number of test questions must give him the amount of questions he got right--that's to say, 8. So, we can right 0.64n=8, where n is the total number of test questions. Divide both sides by 0.64, to get n=8/0.64, right? Now we've solved for n, which is the total number of test questions.

anonymous · Answer

Okay, I understand.  Thank you.