Answers to the exercises are available here.

Exercise 1

What is the output of:
ifelse(sqrt(9)<2,sqrt(9),0)

Exercise 2

What is the output of:
ifelse(sqrt(100)>9,sqrt(100),0)

Exercise 3
What is the output y of:
x=12
if(is.numeric(x)) y=x*2

Exercise 4

What is the output x,y of:

z=-1
if(z<0){x=abs(z);y=z*3}

Exercise 5

What is the output y of:
z=6
if(z<0) y=z*3 else y=z*5

Exercise 6

What is the output z of:
x=15
y=3
if(is.numeric(x)) if(is.numeric(y) & y!=0) z=x/y

Exercise 7

What is the output of:
x=letters[20]
if (is.numeric(x)) print('is numeric') else if(is.character(x)) print('is character')

Exercise 8

What is the output of:
x=90 ifelse(x<100,ifelse(x/2==trunc(x/2),x/2,0), ifelse(x/100==trunc(x/100),x/100,-1)) x=120 ifelse(x<100,ifelse(x/2==trunc(x/2),x/2,0), ifelse(x/100==trunc(x/100),x/100,-1)) x=200 ifelse(x<100,ifelse(x/2==trunc(x/2),x/2,0), ifelse(x/100==trunc(x/100),x/100,-1))

Exercise 9

What is the output n of:
z='i' if (z %in% letters) if (z=='a') n=1 else if (z=='e') n=2 else if (z=='i') n=3 else if (z=='o') n=4 else n=5

Exercise 10

What is the output n of:
z='u' if (z %in% letters) if (z=='a') n=1 else if (z=='e') n=2 else if (z=='i') n=3 else if (z=='o') n=4 else n=5