Look at . WHY?
Ok, this one is giving me some problems:
Qu. On a bookshelf there are works by three authors, three volumes by Gilmore, three
volumes by Lawson and one volume by Patterson. If the books are placed at
random on the shelf, the probability that the volumes of the same author are
I could find the probability that three books from Gilmore are together, the separate probability that the books from Lawson being together, but I don't know how to find the intersection between those two sets of probabilities...
P(3 Gilmore together) =
P(3 Lawson together) =
P(3 Lawson together and 3 Gilmore together) =
Total probability =
How can I solve this?
Um... I thought of it like this:
(G G G) (L L L) P
G permute among themselves, so 3!
L permute among themselves, so 3!
Then, there are three major items, so permuting again gives 3!
Finally, total different arrangements = 7!
So, I get ((3!)^3)/7!
Or... did I miss something?
EDIT: Ok, I'll see that tomorrow... bedtime here...
Ok, I admit that I don't quite know what the question is really asking for.
If the volumes of each author needs to be grouped together, then the answer is only 3/70. So, this is the answer then?
It's so hard to understand what is required to find by the question...