18. What is the r code for checking missing values in a dataset?
(A) is.na(Bat) <- Bat==""
(B) colnames(Bat)[apply(is.na(Bat), 2, any)]
(C) Bat[is.na(Bat)]=Mode(Bat)
(D) Bat[is.na(Bat)]=mean(Bat,na.rm=TRUE)
19. A statistician stored data in R and named it BreastCancer_dat. The columns of the data are age, weight,
blood, glulevel, and education. What is the r code for selecting the weight column?
(A) Breast.Cancer_data$weight
(B) breastCancer_data$weight
(C) BreastCancer_dat$weight
(D) Breast.cancer$data$weight
20. There is a matrix named Flower in R with 3 rows and 4 columns. What is the r code for selecting only the
third column?
(A) Flower[, 2] (B) flower[3, ]
(C) A[, 3]
(D) Flower[, 3]