Answer:
The standard deviation of the heights of the group of trees is 3 feet
Step-by-step explanation:
For a normal distribution, the z-score corresponding to a particular observed value is calculated as;
z-score = (observed value - mean) / (standard deviation)
The mean is given as 14.3
The z-score is 1.9
The observed value is 20 (the given height)
We can make the standard deviation to be the subject of the formula in the above equation;
standard deviation = (observed value - mean) / ( z-score)
We then substitute the given values into this equation;
standard deviation = [tex]\frac{20-14.3}{1.9}=3[/tex]
