Anser the following questions: Problem $1$

Let x $<-$ c$(2,-3,4),$ y $<-$ c$(-6,-12,7,5),$ and z $<-$ c$($x$,$ NA$,$ y$).$ Then the length of the vector t $<-$ z$[-$c$(1,3,7)]$ is$?$

A$.7$

B$.5$

C$.6$

D$.9$

Answer:

Problem $2$

Let x $<-$ c$(0\mathrm{.}25,2\mathrm{.}61,5),$ y $<-$ c$(-3,,4,-12),$ and z $<-$ c$($x$,$ y$,$ NA$).$

What is the result of executing the code z$[6]$

A$.4$

B$.5$

C$.$ NA

D$.-12$

Answer:$\_\_\_\_\_\_\_\_$

problem $3$

Let A $<-$ matrix$(1$:$20,$ nrow$=4,$ byrow $=$ TRUE$)$

What is the result of executing the code A$[2,3]$

A$.5$

B$.7$

C$.8$

D$.9$

Answer:$\_\_\_\_\_\_\_\_$