M, D, R, P, and Q are all of different weights. R is lighter than only M. P is lighter than Q and D. Which of them is the second lightest?

In an examination, P, Q, R, and S each scored different marks. Q scored more than R and S. No one scored less than P. Who among them scored the maximum marks?

In a row of people facing north, P is 2nd from the right end and Q is 7th from the right end. Q is exactly between P and R. If R is 5th from the left end of the row, how many people are there in the row?