Question 1182168
Total number of marbles: 4+3+6 = 13<br>

a) There are 4 outcomes (of 13 possible) for choosing blue:  4/13 for choosing blue.
That leaves 12 marbles in the bag, of which 6 are red, so 6/12 for choosing red on the 2nd choice.<br>
  
P(blue then red) = (4/13)*(6/12) = 2/13 <br>

Parts (b) and (c) are solved in a similar manner.