Format
A question is followed by two statements, I and II. You do not need the answer itself - only whether the statements give enough data. The five standard options are:
- Statement I alone is sufficient, II alone is not.
- Statement II alone is sufficient, I alone is not.
- Either I alone or II alone is sufficient.
- Both I and II together are necessary.
- Even I and II together are not sufficient.
Topics used: seating, ranking, blood relations, directions, coding, days and floors.
Method
- Read the question and note exactly what must be fixed (one person, one direction, one code).
- Test statement I alone. Is there only one possible answer? Write "I: yes/no".
- Test statement II alone, forgetting I completely. Write "II: yes/no".
- Only if both are "no", combine them and test again.
- Map the results: yes/no = option 1; no/yes = 2; yes/yes = 3; no/no but together yes = 4; otherwise 5.
Worked example
Question: Who is the tallest among P, Q, R, S and T? I. P is taller than Q and R, and T is shorter than S. II. S is taller than P. From I, the tallest is P or S - not sufficient. From II alone, nothing is said about Q, R and T - not sufficient. Together: S > P > Q, R and S > T, so S is the tallest. Answer: both together are necessary.
Trap: do not carry information from statement I into your test of statement II. Also, "cannot find the exact answer but can find a yes/no" still counts as sufficient for a yes/no question.
Common sufficiency checks
- Blood relation: a statement that leaves the person's gender unknown is usually insufficient for "son/daughter" type questions.
- Coding: a word is fixed only if it is the sole word common to two sentences.
- Direction: both direction and distance of each link must be known; a distance without a direction is not enough.
- Position: "12th from the right" is useless for "position from the left" unless the total is known.
Time target
40-60 seconds per question. Never solve fully when a quick check shows two possibilities - two answers already means "not sufficient".