SOLUTIONS Lab1:

a)

> grades<- matrix(c(20,23,18,48,16,15,18,40,25,20,22,40,14,19,18,42),byrow=T,
 nrow=4,dimnames=list(NULL,c("Test1","Test2","Test3","Final")))

 grades
     Test1 Test2 Test3 Final 
[1,]    20    23    18    48
[2,]    16    15    18    40
[3,]    25    20    22    40
[4,]    14    19    18    42

b)

> grades<- rbind(grades,c(10,15,14,30))
> grades
     Test1 Test2 Test3 Final
[1,]    20    23    18    48
[2,]    16    15    18    40
[3,]    25    20    22    40
[4,]    14    19    18    42
[5,]    10    15    14    30

c)

> grades[5,2]<-17
> grades
     Test1 Test2 Test3 Final 
[1,]    20    23    18    48
[2,]    16    15    18    40
[3,]    25    20    22    40
[4,]    14    19    18    42
[5,]    10    17    14    30

d)
> grades[,3]

 18 18 22 18 14

e)

> grades[grades[,1]>16,4]
[1] 48 40

f)

> grades[,-3]
     Test1 Test2 Final
[1,]    20    23    48
[2,]    16    15    40
[3,]    25    20    40
[4,]    14    19    42
[5,]    10    17    30

g)

> nrow(grades)
[1] 5