check my answer: Thank you

Seniors at a local high school took both the AP Statistics exam and the AP Literature exam. On the Statistics test, the mean score was 2.4 with a standard deviation of 0.6. On the Literature test, the mean score was 2.65 with a standard deviation of 0.55. If you wanted to look at the combined scores (and assumed the tests were independent), what would their mean and standard deviation be?

these are the given answers:
A. 5.05, 0.66
B. 5.05, 1.15
C. 5.05, 1.07
D. 5.05, 0.82

Question

check my answer: Thank you

Seniors at a local high school took both the AP Statistics exam and the AP Literature exam. On the Statistics test, the mean score was 2.4 with a standard deviation of 0.6. On the Literature test, the mean score was 2.65 with a standard deviation of 0.55. If you wanted to look at the combined scores (and assumed the tests were independent), what would their mean and standard deviation be? 

these are the given answers: 
A.  5.05, 0.66 
B.  5.05, 1.15 
C.  5.05, 1.07 
D.  5.05, 0.82  <---
E.   5.05, 0.42

howard-wolowitz · Answer

@mathmale  can you shed some light

mathmale · Answer

Hello, Howard.  Here you're dealing with 2 different variable concurrently.  There are definitely techniques for figuring out joint probability (like this), and you may uncover what you need by googling "joint probability calculations" or "joint probability mean" or "joint probability standard deviation."  I have no references here with me, unfortunately, so will have to ask you to try those searches.  Good to be in touch.