Distribute on the left side
7.4a+22.2=3.2a+43.2
Subtract 3.2a from both sides
4.2a+22.2=43.2
Subtract 22.2 from both sides
4.2a=21
Divide both sides by 4.2
a=5
3/18 divided 7/21 =3/18 multiply by 21/7 (we have to flip the second fraction and multiply by 3/18)= 63/126=1/2
So the answer is 1/2
The sample % of these two populations would be 100/size (of student body at each school) x 100 so this would compare the two student bodies preferences for the particular type of candy bar. However, the actual % of the whole student body at each school would be a factor also. If the high school only had 200 students then this would be 50% representative but if the middle school had say 500 students this would only be 20% representative so this would have to be taken into account too. It might be more representative to have the same % of the student bodies respectively for the sample.
The greatest common divisor of these numbers is 12.
