Question

When starting a new unit, a teacher announces that each day after the first, the class must do twice the total number of problems that had been assigned on all previous days. The class works for 6 days and on the 7th day she says that this is our last day of the unit. On that last day, what fraction of the problems do they still have to complete.

Answer 1

1st day: x
2nd day: 2x
3rd day: 2(x+2x)= 6x
4th day: 2(x+2x+6x)=18x
And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on. And so on.

Answer 2

Hope you don't mind :)