Question

1. The built-in data “trees” provide the measurements of diameter (Girth), height and volume of trees. These are in inches for Girth, feet for Height and cubic feet for Volume. We will focus on Girth and Height. Write a function convert() that converts the values into the metric system (meters). Your function should take as arguments the value to convert and the unit it was expressed in (inches or feet) (use the following: x inches = x*0.0254 meters, x feet = x*0.3048 meters). If the first argument is not numeric or if the second argument is not “inch” or “feet”, use stop() function with an error message. Here is how it should work:

> convert(8.3,"inches")

[1] 0.21082

> convert(8.3,"feet")

[1] 2.52984

> convert(8.3,"foot")

Error in convert(8.3, "foot") : the unit was not "inches" or "feet"

Use your function to convert the values of Girth and Height to meters. Using cor.test() function, calculate the correlation (and the corresponding p-value) between Girth and Height in meters.

Answer 1

The R code is

convert=function(x,unit){
if(unit=="inches") x*0.0254 else if(unit=="feet") x*0.3048
else stop('the unit was not in "inches" or "feet"')
}
convert(8.3,"inches")
convert(8.3,"feet")
convert(8.3,"foot")
d=trees
attach(d)
Girth=convert(Girth,"inches")
Height=convert(Height,"feet")
cor.test(Girth,Height)

The Output is

#Here Value of Correlation coefficient is 0.5192801

#From P-Value =0.002758<=0.05 There is enough evidence to claim the population correlation coefficient is not zero.The Regression coefficient is significant