a student answers 90% of he questions on a math exam correctly. if he answers 18 questions correctly, how many questions are on the exam?

Question

how do i solve his and how do i get my answer correct? whats an easy way to memorise how to do these problems?

Answer 1

Easiest way to approach this is to remember the percentage proportion equation. Part/Total= percentage/100. 

With that in mind just plug in to the equation and find what you're missing. In this case it would be 18/x (because you are trying to find the total amount of questions) = 90/100. Solve for X and you got your answer. 

 

18/x=90/100

18/x=.90

x=18/.90 

x=20 

Therefore the exam has 20 questions.