Question

Please can You Help!
There are six books in a row. Person A picks one of the books at random. Then Person B picks a book at random from the five books that remain.
i)Find the chance that they pick books that are next to each other.
My approach had been:
product rule with condisionality;
P(A-book1 and B-book2)=P(A)*P(B\A) for all A and B.
P(A and B)= (1/6)*(1/5)= Yet it's wrong???

Answer 1

yes, it is wrong. I think it will be more simple in this way:
as there are 6 books, pair of books which are next to each other can be chosen in 5 ways
but you can select 2 books from 6 in 6C2 ways=15 ways
so, the probability is 5/15=1/3

Answer 2

Thanks! Arnab09!

Answer 3

you are most welcome :)