If P = 3, R = 27, T = 243, then Q = S = ______
A. 80 B. 80 C. 90 D. 110
GATE 2020 · General Aptitude · Sequence Series · medium
Answer: Q + S = 9 + 81 = 90
Identify the pattern in given terms: The odd-position terms P, R, T correspond to 3^1, 3^3, 3^5 respectively. The exponents are consecutive odd numbers.
Determine even-position terms Q and S: Even positions use even powers of 3: Q = 3^2 = 9 and S = 3^4 = 81. The full sequence is 3, 9, 27, 81, 243 - a geometric sequence with common ratio 3.
Compute Q + S: The question asks for Q = S = ___ which represents Q + S = 9 + 81 = 90.