Choose symbol sequence — Replace * to balance: 7 * 7 * 2 * 1 = 12
Verbal Reasoning
Mathematical Operations
Difficulty: Medium
Choose an option
-
Ax - ÷
-
B+ - x
-
Cx - +
-
D+ x -
Answer
Correct Answer: + - x
Explanation
Introduction / Context:We must select a fixed sequence of three operators to make the equation true. Standard precedence applies.
Given Data / Assumptions:
- Template: 7 {s1} 7 {s2} 2 {s3} 1 = 12.
Concept / Approach:Test reasonable combinations; subtraction and multiplication often help reach small targets like 12.
Step-by-Step Solution:
Option B (+ - ×): 7 + 7 - 2 × 1 = 14 - 2 = 12 → true.Other options do not yield 12 under precedence.Verification / Alternative check:Explicitly compute each alternative; only Option B balances.
Why Other Options Are Wrong:
- They produce values like 47, 12 by chance only if precedence is ignored, or other mismatches.
Common Pitfalls:
- Ignoring that × takes precedence over +/−.
Final Answer:+ - x