$1.$ What spreadsheets exist in the workbook? $2.$ Import mbta.xlsx$13.$ When importing the data, interpret the string $$NA$$ as missing values.

library$($readxl$)$

excel$\_$sheets$($path $=\_\_\_\_\_\_\_\_\_)$

mbta $<-$ read$\_$excel$($path $=\_\_\_\_\_\_\_,$ skip $=\_\_,$ na $=\_\_)$

Exercise $2-$ Exam the data

The first step when cleaning a data set is to explore it a bit. Pay particular attention to how the rows and columns are organized and to the locations of missing values.

$1.$ View the structure of mbta.

$2.$ View the first $6$ rows of mbta.

$3.$ View a summary of mbta.

$4.$ How many missing values are in each column? If you see zero that means you didn$$t complete exercise $1\mathrm{.}3$ correctly.