Answer the questions based on the information given below. Seven books M, N, O, P, Q, R and S are arranged in a row from left to right (where Left = Front/Ahead and Right = Back/Behind). S is kept ahead of Q and R. As many books are kept ahead of S as behind R. M is kept behind Q but ahead of P. P is not the last book in the row and N is not the first book in the row. O is kept behind N and
M. Only one book is not kept ahead of Q. How many books are kept ahead of M?

S is kept ahead of Q and R. S   Q/R  R/Q As many books are kept ahead of S as behind R. _____  _____  S   Q   R ____  ____  …… (I) _____  S      Q     R   ____  …… (II) S      Q     R   …… (III)   M is kept behind Q but ahead of P. P is not the last book in the row and N is not the first book in the row. O is kept behind N and M. Only one book is not kept ahead of Q. Case I and II will get discarded. _____  _____  S   Q   R M  P  …… (I) _____  S       Q     R   ____  …… (II) S      N   Q     M    O/P   P/O     R    …… (III)   Therefore, the final arrangement is: S      N      Q       M      P/O       O/P     R