text: # A box contains 5 red, 2 white, & 3 blue marbles. If a marble is selected at random, what is the probability that it is red or white?
  
  May 3, 2018
  
  $\frac{7}{10}$
  
  #### Explanation:
  
  Probability that it is red =$\frac{5}{10}$
  Probability that it is white =$\frac{2}{10}$
  
  So the probability that it is red or white =$\frac{5}{10} + \frac{2}{10} = \frac{7}{10}$
  
  Another way
  
  Probability that it is red or white is the same as it NOT being blue
  Probability that it is blue =$\frac{3}{10}$, so the probability that it is NOT blue =$1 - \frac{3}{10} = \frac{7}{10}$