Answer:
15.87% portion of oak trees in this forest have a circumference greater than 21 inches
Step-by-step explanation:
Given that
Mean = μ = 19.7 inches
SD = σ = 1.3 inches
We have to find the probability of circumference greater than 21 inches
Let x = 21 inches
First of all we have to find the z-score of the value
z-score is given by the formula
[tex]z = \frac{x-mean}{SD}[/tex]
Putting the values
[tex]z = \frac{21-19.7}{1.3}\\z = \frac{1.3}{1.3}\\z = 1[/tex]
We will use the z-score table to find the probability of x<21
P(z<1) = 0.8413
The value gives us the area under the curve up till that value
To find the greater than probability, we have to subtract less than probability from 1.
P(z>1) = 1 - P(z<1) = 1 - 0.8413 = 0.1587 => 15.87%
Hence,
15.87% portion of oak trees in this forest have a circumference greater than 21 inches
