Consider a computer system with three users, Alice, Bob and Cindy. Alice owns the file alicerc, and Bob and Cindy can read it. Cindy can read the write the file bobrc, which Bob owns, but Alice can only read it. Only Cindy can read and write the file cyndyrc, which she owns. Assume that the owner of each of these files can execute it.

a. Create the corresponding access control matrix.

b. Cindy gives Alice permission to read cyndyrc, and Alice removes Bob's ability to rad alicerc. Show the new access control matrix.

1. the program must provide following functions to extract some statistics. note that the data_list parameter specified in these functions may be the same for all functions or different for different functions—that is your choice. a skeleton file is provided on mirmir. a) open_file()prompts the user to enter a year number for the data file. the program will check whether the year is between 1990 and 2015 (both inclusive). if year number is valid, the program will try to open data file with file name ‘year.txt’, where is the year. appropriate error message should be shown if the data file cannot be opened or if the year number is invalid. this function will loop until it receives proper input and successfully opens the file. it returns a file pointer and year. i. hint: use string concatenation to construct the file name b) read_file(fp)has one parameter, a file pointer read. this function returns a list of your choosing containing data you need for other parts of this project. c) find_average(data_list) takes a list of data (of some organization of your choosing) and returns the average salary. the function does not print anything. hints: i. this is not the average of the last column of data. it is not mathematically valid to find an average by finding the average of averages—for example, in this case there are many more in the lowest category than in the highest category. ii. how many wage earners are considered in finding the average (denominator)

Write a method named addall that could be placed inside the hashintset class. this method accepts another hashintset as a parameter and adds all elements from that set into the current set, if they are not already present. for example, if a set s1 contains [1, 2, 3] and another set s2 contains [1, 7, 3, 9], the call of s1.addall(s2); would change s1 to store [1, 2, 3, 7, 9] in some order. you are allowed to call methods on your set and/or the other set. do not modify the set passed in. this method should run in o(n) time where n is the number of elements in the parameter set passed in.

An environmental protection agency study of 12 automobiles revealed a correlation of 0.47 between engine size and emissions. at 0.01 significance level, can we conclude that there is a positive association between the variables? what is the p value? interpret.