We have the given in the problem as mentioned:
A total of 130 students and only 7 had been placed in the wrong math class.
With this given, we can easily draw the proportion of all students who have been placed in the wrong math class by estimation method and the solution is shown below:
Proportion = 7/130
1279???
Because the gcf does not leave any remainders behind. The gcf could be 1280, but that would not leave a remainder behind if you divided 1280 by 1280. So, I think it is 1279, but i am probably wrong
