Try this TOMATO problem from I.S.I. B.Stat Entrance Objective Problem based on Logic and True-False.
Let P,Q,R,S be four statements such that if P is true then Q is true, if Q is true then R is true and if S is true then at least one of Q and R is false then it follows that
But try the problem first...
Answer: if at least one of Q and R is true then S is false
B.Stat Objective Question 65
Challenges and Thrills of Pre-College Mathematics by University Press
P true implies Q true and Q true imples R true
S true implies Q false with R false
then R true implies Q true implies P true with S false then if at least one of Q and R is true then S is false.