One square mile of forest is divided up into ten equally sized quadrats, 1/10th of a mile each. in quadrat #3, twenty-five pine trees are counted.   what would be a reasonable estimate for the total number of pine trees in the larger plot of land (one square mile or forest)?

250 pine trees

Explanation:

If we have a one square mile of forest that is divided into ten equally sized quadrants, that means that each of them accounts for 1/10th of a mile. If in one of the quadrants there are twenty-five pine trees, and if that is the number of pine trees in all of the quadrants, then we can easily come to the result for the whole forest. As each quadrant is 1/10 of the whole area, it means that the number of pine trees in one of them should be multiplied by the number of quadrants:

25 x 10 = 250

We get a result of 250 pine trees for the whole forest area of one square mile.