Define the variables for the following situations. For each variable, indicate w

Question

Define the variables for the following situations. For each variable, indicate whether it is quantitative or qualitative, and independent or dependent, where appropriate:

2. Maple tree diameters in a forest area are normally distributed with mean 10 inches and standard deviation 2.2 inches. a. Estimate the percent of trees having a diameter greater than 15 inches. Justify your answe b. Calculate the z-score for a tree with diameter of 3.4 inches. Show your work. c. Find the exact percentile rank of the trees that have a diameter below 3.4 inches.

Explanation / Answer

Mean ( u ) =10
Standard Deviation ( sd )=2.2
Normal Distribution = Z= X- u / sd ~ N(0,1)                  
a.
P(X > 15) = (15-10)/2.2
= 5/2.2 = 2.2727
= P ( Z >2.273) From Standard Normal Table
= 0.0115
b.
Z = (3.4-10)/2.2
= -6.6/2.2= -3
c.
P(X < 3.4) = (3.4-10)/2.2
= -6.6/2.2= -3
= P ( Z <-3) From Standard Normal Table
= 0.0013                  
                  

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.