# probability or odds, not sure which it is

• Jun 27th 2010, 10:40 AM
thefuzz250
probability or odds, not sure which it is
I have 338 songs on my ipod. There are 17 songs from artist X. What are the odds a song from artist X will play? What are the odds 5 songs from artist X will play in a row given the ipod is still playing at random?

For the life of me I cannot remember how to do this, thanks!
• Jun 27th 2010, 12:09 PM
Dmitry
for the first one, if we are talking about the very next song, the probability that the author of it is X would be 17/338. So the odds would be 17/(338-17).

second one, if we assume that once the song was played in can no longer be repeated:

17*16*15*14*13
--------------------------- = 0.000000173 This is the probability that there would be 5 songs by X in a row. => The probability that there would not be such situation is 0.999999827.
338*337*336*335*334

=> the odds would be 0.000000173/0.999999827

otherwise, if repetition is allowed,

P (5songs in a row) = (17/338)^5, the probability of the opposite one is 1-(17/338)^5. => odds would be ((17/338)^5)/(1-(17/338)^5)