Question 6
Dương has three pebble piles initially containing 10,20,60 pebbles. Each move takes one pebble from each of two piles and puts both into the remaining pile. (a) After 10 moves, the destination piles have been pile 1 three times, pile 2 four times, pile 3 three times. How many pebbles are in each? (b) Can any finite sequence make the three piles equal? Explain.
