Last year the 6th grade had 350 students. This year the number of students decreased by 36%. How would you set up this proportion?

Question

I have to set up a proportion similar to percent of chane which is the difference of two given numbers over the original number, cross multiplied with "x" over 100. For example. 56-31 equals 25. So 25 would go over 56. Correct? Then you would cross multiply with x over 100. 

 

25      x 

56 = 100  =   2,500=56x      2,500/ 56 = 44.6% rounded to the nearest tenth. But my teacher says it's not the same 

                   56        56        proportion... I have no idea how to do this and I've been stressing over it for days!!! help???

Answer 1

x=# of students less that you have this year

(350-x) is the number of students you have this year and 350 is the number of students you had last year

to find the percent of decrease, you subtract this year's total from last year's total and put that over last year's total

 

[350-(350-x)]/350

[350-350+x]/350

x/350=the percent of decrease which you state is 36%

x/350=36/100

you can simplify before you cross multiply if you want to (x/350=9/25)

if not, 100x=36*350

100x=12,600

x=12,600/100

x=126 less students

350-126=224 students this year

Simply speaking, x, the number of students less this year is 36% of 350.

x/350=36/100 again