Wood-Burning Example
Suppose that the amount of wood that I burn per day is approximately normally distributed with a mean of 16 ft\(^3\) and a standard deviation of 4 ft\(^3\). Use this information to answer the questions below.
- What is an individual?
- What is the variable and what type of variable is it?
- On what proportion of days do I burn less than 22 ft\(^3\) of wood?
- On what proportion of days do I burn more than 15 ft\(^3\) of wood?
- On what proportion of days do I burn between 11 and 26 ft\(^3\) of wood?
- What is the amount of wood burned per day such that I burn less than that amount on 10% of the days?
- What is the amount of wood burned per day such that I burn more than that amount on 20% of the days?
- What are the most common 50% of amounts of wood burned per day?
Load NCStats Package
library(NCStats)
Forward, Less-Than
( distrib(22,mean=16,sd=4) )
## [1] 0.9331928
Forward, Greater-Than
( distrib(15,mean=16,sd=4,lower.tail=FALSE) )
## [1] 0.5987063
Forward, Between
( ab <- distrib(26,mean=16,sd=4) )
## [1] 0.9937903
( a <- distrib(11,mean=16,sd=4) )
## [1] 0.1056498
ab-a
## [1] 0.8881406
Reverse, Less-Than}
( distrib(0.1,mean=16,sd=4,type="q") )
## [1] 10.87379
Reverse, Greater Than
( distrib(0.20,mean=16,sd=4,type="q",lower.tail=FALSE) )
## [1] 19.36648
Reverse, Between
( distrib(0.25,mean=16,sd=4,type="q") )
## [1] 13.30204
( distrib(0.25,mean=16,sd=4,type="q",lower.tail=FALSE) )
## [1] 18.69796