• Reasoning Ability - Syllogisms
Question

Statements :  All windows are doors.
                        All entrances are windows.
                        No gate is a door.

Conclusions : I.    At least some windows are gates.
                        II.   No gate is an entrance.    

  • A) if only conclusion I follows.
  • B) if only conclusion II follows.
  • C) if either conclusion I or conclusion II follows.
  • D) if neither conclusion I nor conclusion II follows.
  • E) if both conclusion I and conclusion II follow.
Solution
B

All entrances are windows (A) + All windows are doors (A) + [No gate is a door (E)] = No door is a gate (E) = A + E = E = No entrance is a gate.

Hence, conclusion II follows .

Again,

All window are doors (A) + [No gate is a door (E)] = No door is a gate (E) =  A + E = E = No window is a gate.

Thus, conclusion I does not follow.

Hence, option B is correct.

B

All entrances are windows (A) + All windows are doors (A) + [No gate is a door (E)] = No door is a gate (E) = A + E = E = No entrance is a gate.

Hence, conclusion II follows .

Again,

All window are doors (A) + [No gate is a door (E)] = No door is a gate (E) =  A + E = E = No window is a gate.

Thus, conclusion I does not follow.

Hence, option B is correct.
Comments