# Math Help - Find the mean and standard deviation of the sum or difference of independent random v

1. ## Find the mean and standard deviation of the sum or difference of independent random v

what should i do for A?? and for B, is it asking me to convert all the temperatures to Fahrenheit?

2. ## Re: Find the mean and standard deviation of the sum or difference of independent rand

They are asking for $E[X-550]$, and $\textrm{Var}(X-550)$. You should have some formulas that should make the preceding quite simple.

3. ## Re: Find the mean and standard deviation of the sum or difference of independent rand

yes i figured out how to get the mean... i just simply take the temperatures that are off target and minus it to 550... i got that part but what i don't know how to get is the standard deviation.... would you happen to know how to calculate that based on my problem??