Jenny has three bags, one white, one yellow ,one orange. each bag contains 20 identically sized balls. the white bag has 5 blue balls the yellow bag has 10 blue balls and the orange bag has 15 blue balls. The rest of the balls are red.

she now draws balls from the bags one ball each time and replacing each ball picked before picking the next.

If a blue ball is picked from the white bag jenny next picks from the yellow bag otherwise she next picks from orange bag. If a blue ball is picked from the yellow bag jenny next picks from the orange bag, otherwise she next picks from white bag, otherwise she next picks from yellow bag.

If jenny starts her draw from the white bag, compute the probablity that

a)the first 4 balls she drew are blue

b)after 5 draws she has not drawn from the orange bag.