A big department store has two entrance doors, one on 5th Ave. and the other on 6th Ave. The number of shoppers who enter the store through the 5th Ave. door in an hour, X, has mean of $\displaystyle \mu_{{X}}={25}$ and standard deviation $\displaystyle \sigma_{{X}}={5}$, and the number of shoppers who enter the store through the 6th Ave. door in an hour, Y, has a mean of $\displaystyle \mu_{{Y}}={35}$ nd standard deviation of $\displaystyle \sigma_{{Y}}={8}.$ Let the random variable T be the total number of shoppers who enter the store in an hour.

1. What is $\displaystyle \mu_{{T}},$ the mean of T?
   
   30
   

   42
   

   10
   

   60
   
2. Assuming that shoppers enter the store through the two doors independently, what is $\displaystyle \sigma_{{T}}$, the standard deviation of T?
   |
   13
   

   89
   

   $\displaystyle \sqrt{{{13}}}$ 
   

   $\displaystyle \sqrt{{{89}}}$