The density of Douglas firs in an old-growth forest is estimated by counting the Douglas firs in four sample plots of 1 hectare each. The number of fir trees in the plots is 10, 12, 7, and 11, respectively. What is the estimated density of firs in the forest?

10 trees per hectare

Explanation:

It is given that the density of Douglas firs is estimated by counting them in four sample plots of each one hector.

And the number of trees in each hector of the forest lands are - - - 10, 12, 7, and 11, respectively.

Therefore in order to find the estimated number of tress or density of Douglas firs in the forest by taking the average number of tress in these four hectors. This will give us an estimated density of Douglas firs across the forest.

Therefore, (10 + 12 + 7 + 11) / 4 = 40 / 4

= 10

Therefore there are 10 Douglas fir trees in each hector.

Thus the answer is - -

10 trees per hectare