General Studies · Puzzles

Six boxes P, Q, R, S, T, and U are stacked one above the other in a single vertical column, but not necessarily in the same order. Box P is placed somewhere above Box R but not necessarily immediately above it. Box S stacked somewhere above Box U but not immediate above. Box Q is neither at the top nor at the bottom of the stack. Box T is placed immediately below Box P. Box R is placed third from the bottom. Number of boxes between S and U double the number of boxes between Q and P. How many boxes are kept between S and R?