$2.$ Give the R commands to do the following:

$($a$)$ Use rep$()$ to create a vector that has the following elements: $2\mathrm{.}7,8\mathrm{.}0,3\mathrm{.}0,2\mathrm{.}7,$

$8\mathrm{.}0,3\mathrm{.}0.$

$($b$)$ Use seq$()$ with the length.out argument to create a vector that has the following

elements: $0\mathrm{.}0,0\mathrm{.}5,1\mathrm{.}0,1\mathrm{.}5,2\mathrm{.}0.$

$($c$)$ Let x be a vector of length three or greater that contains numeric elements. Write

some R commands that calculate the sample mean of all of the elements of x

except the smallest and largest. For example, if x $=(1,2,4,5,6,7),$ you should

output the mean of $(2,4,5,6).$ If x $=(1,1,2,3,4,4),$ you should output the

mean of x $=(2,3).[$Hint: Make use of which, min, max, mean.$]$

$($d$)$ Let x be a vector containing numerical elements, each of which is a positive integer.

Write a single line of R code that replaces each element that is a perfect square

with zero. For example, if x$=(1,2,3,4),$ then you should return $(0,2,3,0).$