Consider moving of the 1 book from shelf A to shelf B as the 1st event that is followed by student picking a book from shelf B as the second event.
P(Student picking a chemistry book from shelf B) = P(Moving a chemistry book from shelf A to shelf B) * P(Student picking a chemistry book from shelf B)
= 1/8* 1/6 ( There are total 8 books of which 1 is chemistry book and after the move, there will be 1 chemistry book in the new number of books (6) in shelf B)
= 1/48
Hence answer is C
Hope this helps.
P(Student picking a chemistry book from shelf B) = P(Moving a chemistry book from shelf A to shelf B) * P(Student picking a chemistry book from shelf B)
= 1/8* 1/6 ( There are total 8 books of which 1 is chemistry book and after the move, there will be 1 chemistry book in the new number of books (6) in shelf B)
= 1/48
Hence answer is C
Hope this helps.