the answers should be in R code

- Try to access the dataset "Nile" which contains the water supply of Nile from 1871 to 1970 and find out the mean of water supply.

- In the class, we have already learnt how to import data stored in a CSV file. Try to import data from members.csv and do some basic manipulation as taught in lecture.

- The "obama_vs_mccain" dataset contains the fractions of people voting for Obama and McCain in the 2008 US presidential elections. Use the data to draw a histogram to show the distribution of the percentage of votes for Obama. Define the number of bins to be 4.

- Use iris dataset, which is available in R. Do the following steps: (a) Make a boxplot of Sepal.Width stratified by Species. (b) Change the range of the y-axis so it starts at 2 and ends at 4.5. (c) Modify the boxplot function so it doesnt draw ticks nor labels of the x and y axes. (d) Add notches to the boxes in the plot. (e) Increase the distance between boxes in the plot. (f) Change the color of the box borders to blue, the color of the median lines and the outlier points to red. (g) Add title to the boxplot. (h) Add x-axis, y-axis label and y-axis ticks to the boxplot.

- Simulate 500 standard normal random variables, with mean=100 and standard deviation=15. Find P(X= 100), P(X<= 100) and the 35th percentile of the distribution. Draw the histogram of the random variables, and add the density curve to the graph.