in R code please

Construct a vector xol n = 100 values from the Normal distribution where 3 and o=5. (a) Construct a numeric vector g which consists of five Is, followed by five 2s and so on up to five 20s (hinterp). Then use tapply to construct a vector y of length 20, where y(i) is the mean of the first 5 values in y[2] is the mean of the next 5 values in x, and so on. (b) Unos for loop to give an alternative construction for the vectory (c) Plot i verwus index