Create a vector of 10 random normal values using the three following

methods.

(a) Create and concatenate successively the 10 random values with c.

(b) Create a numeric vector of length 10 and change its values successively.

(c) Use the most direct method.

Compare the timings of these three methods (see ?system.time)and

explain the differences.

Repeat this exercise with 10,000 values.