The probability density function shown models the amount of rainfall per year for a certain location. If the area of each square on the grid is 0.05, estimate the probability that the rainfall for the year is less than 8 inches.

Explanation:

The probability that the rainfall for the year is less than 8 inches is equal to the area under the curve of the probability density function to the left of 8 inches.

I attached a graph with the squares that cover that area in red.

There are 7 complete, or almost complete, red squares and 4 triangles.

For estimation purposes, you can count each triangle as half a square.

Thus, consider 7 + 4/2 = 7 + 2 = 9 squares.

Since the area of each square on the grid is 0.05, the area o 9 squares is:

Hence, your estimate of the probability that the rainfall for this year is less than 8 inches is 0.45.