3.19 - 1.99 = 1.20 increase in 4 years
1.20/4 = 0.30
rate of change is 0.30 per year (30 cents per year)
Answer:

Step-by-step explanation:
we know that
The area of the shaded region is equal to the area of triangle plus the area of semicircle
so

we have

Find the height of the right triangle applying the Pythagorean Theorem


The radius of the semicircle is half the height of triangle

substitute in the formula


That number would be 6.
Since 5^2 = 25 and 6^2 = 36, we can see that the only possible whole number between sqrt(27) and sqrt(39) has to be 6.