

```{r}


prop<-read.table("https://math.dartmouth.edu/~m50f17/propellant.csv", header=T, sep=",")
prop <- rbind(prop, c(500,60))
 
plot(prop$Age, prop$ShearS)
fitted<-lm(formula= prop$ShearS ~ prop$Age ) 
abline(fitted$coef, lwd=2, col='blue')



```

```{r}

plot(prop$Age, prop$ShearS)
abline(fitted$coef, lwd=2, col='blue')

prop[21,1]<-2000
points(prop[21,2],prop[21,1], col='red')

fitted<-lm(formula= prop$ShearS ~ prop$Age) 
abline(fitted$coef, lwd=2, col='red')


```

 
