SOLUTION: Five red blocks and 4 white blocks are placed at random in a row. What is the probability that the extreme blocks are both red? I have been struggling with this question for a

Algebra ->  Probability-and-statistics -> SOLUTION: Five red blocks and 4 white blocks are placed at random in a row. What is the probability that the extreme blocks are both red? I have been struggling with this question for a      Log On


   

Question 483680: Five red blocks and 4 white blocks are placed at random in a row. What is the probability that the extreme blocks are both red?
I have been struggling with this question for a while but I am still not getting my textbook's explanation. Would you solve it please and explain yourself?
Thank you very much.
Yours,
Ivanka
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
there are 9C2 ways of selecting the 2 end blocks from the group of 9

there are 5C2 ways of selecting 2 red blocks from the 5 available

so the probability of red at both ends (2 red blocks) is ___ (5C2) / (9C2)

there is no differentiation between "front" end and "back" end in the problem
___ perhaps this is a source of confusion