Fifty white marbles are placed in a row. What is the minimum number
of black marbles that need to be placed between the white marbles such
that each marble (white or black) has at least one neighbour of the
other colour?

1) 24
2) 49
3) 48
4) 25

• 49.
  Black marbles are to be placed between the white marbles. So 1st black will be placed after 1st white. No black to be placed after 50th white. So 49 black marbles needed to be placed.
• 11 years agoHelpfull: Yes(0) No(0)
• wbwwbwwbwwb....wwb
  so 25
• 8 years agoHelpfull: Yes(0) No(0)