In: Statistics and Probability
Question 4: (In this problem first find the probability by using SPSS and copy the output and then calculate the number of trees manually by using the probabilities.)
A certain variety of pine tree has a mean trunk diameter of μ= 150 cm, and a standard deviation of σ= 30 cm which is normally distributed. A certain section of a forest has 500 of these trees. Find Approximately
1. how many of these trees have a diameter smaller than 120
2. how many of these trees have a diameter greater than 160
3. how many of these trees have a diameter between 130 and 160.
4. how many of these trees have a diameter between 120 and 140.
The following information about the mean and standard deviation has been provided:
We need to compute . The corresponding z-value needed to be computed:
Therefore,
We need to compute The corresponding z-value needed to be computed is:
Therefore, we get that
We need to compute . The corresponding z-values needed to be computed are:
Therefore, the following is obtained:
We need to compute . The corresponding z-values needed to be computed are:
Therefore, the following is obtained: