For questions 2 and 3. It is known that the mean diameter of pine trees in a national forest is 9.6 (inches) with a standard deviation 2.4 (inches). Assuming that the tree diameters are distributed normally. If a pine tree is to be selected randomly from this forest, what is the probability that its diameter will fall between 7.2 inches and 14.4 inches?

0.8185

Step-by-step explanation:

Let X represents the tree diameters that are distributed normally.

Given: Mean , Standard deviation  

The probability that its diameter will fall between 7.2 inches and 14.4 inches will be:

Hence, required probability = 0.8185

3

step-by-step explanation:

because where the point where the 2 lines intersect is (3,-1) the x value is 3