hw 9 q2

#Q2
library(MASS)
data(mammals)
? mammals

#(a)
plot(mammals$body,mammals$brain)

#(b)
fit = lm(brain ~ log(body), data = mammals)
boxcox(fit, plotit = TRUE)

boxcox(fit, plotit = TRUE, lambda = seq(-0.05,0.07,by = 0.01))

#(c)
z = lm(log(brain) ~ log(body), data = mammals)
plot(log(mammals$body),log(mammals$brain))
abline(z)

predict(z, data.frame(body=254), interval = "predict")

##        fit      lwr      upr
## 1 6.297125 4.876899 7.717351