x <- read.csv("C:\\Users\\Admin\\Desktop\\SARLAKG\\mba.csv")

attach(x)
dim(x)

## [1] 773   3

colnames(x)

## [1] "data.srno" "workex"    "gmat"

head(x,12)

##    data.srno workex gmat
## 1          1     21  720
## 2          2    107  640
## 3          3     57  740
## 4          4     99  690
## 5          5    208  710
## 6          6    136  660
## 7          7     70  660
## 8          8    103  710
## 9          9     79  700
## 10        10     22  730
## 11        11     69  700
## 12        12     41  740

tail(x)

##     data.srno workex gmat
## 768       768     38  680
## 769       769     88  620
## 770       770    132  670
## 771       771     28  610
## 772       772     10  610
## 773       773     52  620

mean(x$gmat)

## [1] 711.1643

mean(gmat)

## [1] 711.1643

median(gmat)

## [1] 710