## 17.11 Quick revision questions

Consider again the model for tree diameters in Example 17.7 : a normal distribution with $$\mu=8.8$$ inches, and $$\sigma=2.7$$ inches.

1. A tree diameter of 7.9 inches corresponds to a $$z$$-score (to two decimal places) of:
2. The probability that a tree has a diameter less than 7.9 inches is (as a decimal value):
3. The probability that a tree has a diameter greater than 7.9 inches is (as a decimal value):
4. A tree diameter of 9 inches corresponds to a $$z$$-score (to two decimal places) of (as a decimal value):
5. The probability that a tree has a diameter less than 9 inches is (as a decimal value):
6. The probability that a tree has a diameter greater than 9 inches is (as a decimal value):

### References

Aedo-Ortiz DM, Olsen ED, Kellogg LD. Simulating a harvester-forwarder softwood thinning: A software evaluation. Forest Products Journal. 1997;47(5):36–41.