Question

Maple tree diameters in a forest area are normally distributed with mean 10 inches and standard deviation 2.2 inches. Find the proportion of trees having a diameter less than 9 inches.

Answer 1

Answer:

0.32472

Step-by-step explanation:

Maple tree diameters in a forest area are normally distributed with mean 10 inches and standard deviation 2.2 inches. Find the proportion of trees having a diameter less than 9 inches.

The formula for calculating a z-score is z = (x-μ)/σ

where x is the raw score

μ is the population mean

σ is the population standard deviation

z = (9 - 10)/2.2

z = -1/2.2

= -0.45455

Probability value from Z-Table:

P(x ≤ 9) = P(x < 9)

= 0.32472

Therefore, the proportion of trees having a diameter less than 9 inches is

0.32472