The letters L, M, N, O, P, Q, R, S, T in their order are substituted by nine integers 1 to 9 in that order. 4 is assigned to P. The difference between P and T is 5. The difference between N and T is 3. What is the integer assigned to N?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 6
Every letter stands for one of the integers 1 to 9. A difference gives two possible values (add or subtract), and only a value from 1 to 9 can be kept. The three clues are used in turn:
P = 4 (given).
The difference between P and T is 5, so T = 4 + 5 = 9 or 4 − 5 = −1; −1 is not allowed, so T = 9.
The difference between N and T is 3, so N = 9 − 3 = 6 or 9 + 3 = 12; 12 is not allowed, so N = 6.
Note: It seems that there is a mistake in the original NTA paper, which prints “substituted by nine integers 1 to 9 in that order” when it should read “1 to 9 but not in that order”: in that order P would be 5, while the question gives P = 4. The answer comes from the three clues alone.