Question

A middle school had 450 7th grade students last year. this year, there are 30% more 7th grade students. How many total number of students does the school have this year? I know the answer is 585 but when I get to the part to divide by 100, I get lost. I am studying for a test and I am really trying to understand percentage.

Answer 1

The easiest way to do calculations with percentages is to convert them to decimals.

In this case, we have 30%=0.3 more 7th grade students than last year.

Then, if last year we had 450, and this is 100%=1, now we have the 100% of last year (450) plus 30%, that is equivalent to 0.3*450.

We can calculate this as:

$S=450+0.3\cdot450=450+135=585$

Answer: 585 students.