The first step is figuring out the length of the field. To do this, let's work backwards.
We are given the width (11m) and the perimeter (68m). We know that perimeter is measured with the formula P = 2W + 2L or W+W+L+L. All we have to do is plug in our width, 11(2) which is 22, and subtract that from the perimeter:
68 - 22 = 46 < this is the amount of both lengths combined, but in order to find the area, we only need one side. So, divide 46 by 2, and you'll get 23.
Now the area of a rectangle is found by using A = lw. So plug in your numbers and multiply 23 (length) and 11 (width). You should get 253.
The probability of picking a blue envelope is 2/8 = 1/4. You want to select a blue envelope twice with replacement so we multiply 1/4*1/4 which is 1/16.
