Question $1$: Please download the bike sharing data set from the following website:

https:$//$archive$.$ics.uci.edu$/$ml$/$datasets$/$bike$+$sharing$+$dataset. $($I also include the data set on crowdmark.$)$ This dataset contains the hourly and daily count of rental bikes between years $2011$ and $2012$ in Capital bikeshare system with the corresponding weather and seasonal information. There are two data sets and we will use the day.csv$.$ Import the data into $R$ and perform the following exploratory analysis.

a$)$ The variable "registered" records the number of registered users used the bike sharing service on a particular day. Please provide the mean value of the variable "registered" for each day of the week in year $2012.$

b$)$ Plot the conditional density plot of the variable "registered" conditional on each month of the year in year $2012.$

c$)$ Produce a two$-$dimensional levelplot of the variable "registered" against the combination of temperature $($variable "temp"$)$ and humidity $($variable "hum"$).$

d$)$ Write a r function that uses "for" loop to add up the total number of registered users for Year $2012.$

e$)$ Write a r function that uses "tapply" function to get the mean registered users for each combination of $"$yr$"$ and "season".