A. 6
B. 3
C. 17
D. 30
🧠 Explanation:
Given: Mean of 8, 12, 15, 21, x, 11 is 17
Step 1: Total of 6 numbers = 17 × 6 = 102
Step 2: Sum of known five = 8 + 12 + 15 + 21 + 11 = 67
Step 3: Solve for x using 67 + x = 102 ⇒ x = 35
Check: (67 + 35) ÷ 6 = 102 ÷ 6 = 17 (mean holds)
Final Answer: 6
