A random variable x has a mean of 120 and a standard deviation of 15. A random variable y has a mean of 100 and a standard deviation of 9. If x and y are independent, approximately what is the standard deviation of x - y ?.

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's. 

Jane has 3 applesshe gives away 23 - 2 = 1jane has 1 apple lefthope this