There are five boys P, Q, R, S and T standing in a line. Q is taller than T but shorter than P. S is shorter than T but taller than R. Who is the shortest?

Let's represent the height relationships using inequalities:
"Q is taller than T but shorter than P":

P>Q>T
"S is shorter than T but taller than R":

T>S>R
Combining both statements into a single inequality chain:

P>Q>T>S>R
From this comprehensive arrangement, we can see that P is the tallest and R is the shortest boy.