Interchange one pair of signs to make the equation true: 15 ÷ 9 × 3 − 74 + 2 = 5
Verbal Reasoning
Mathematical Operations
Difficulty: Medium
Choose an option
-
A+ and -
-
B÷ and x
-
C+ and ÷
-
D- and ÷
Answer
Correct Answer: + and ÷
Explanation
Introduction / Context:We must find which global swap of a listed pair of operators makes the given equality hold.
Given Data / Assumptions:
- Expression: 15 ÷ 9 × 3 − 74 + 2.
- Goal: value equals 5.
Concept / Approach:Test each candidate swap and compute with precedence.
Step-by-Step Solution:Swap “+” and “÷” (Option C): becomes 15 + 9 × 3 − 74 ÷ 2.Compute: 9 × 3 = 27; 15 + 27 = 42; 74 ÷ 2 = 37; 42 − 37 = 5 ✔.
Verification / Alternative check:Other swaps yield values far from 5.
Why Other Options Are Wrong:They either significantly increase or decrease the total beyond 5.
Common Pitfalls:Ignoring operator precedence when evaluating the swapped expression.
Final Answer:+ and ÷.