Hello, I need help solving this, preferably on paper.

4. Determine the area under the standard normal curve that lies between -2.5 and -2 5. A variable is normallyr distributed with a mean 68 and standard deviation 10. Find the percentage of all possible values of the variable that a} Lies between 3'3 and 80 b] Are at least 7'5 {2} Are at most 90 6. For the following Population data 2,3,5,5,?,3 find: The mean when n=2