In the relation $x > y + z$, $x + y > p$ and $z < p$, which of the following is necessarily true?
Aptitude
Number System
Difficulty: Medium
Choose an option
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A$y > p$
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B$x + y > z$
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C$y + p > x$
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DInsufficient data
Answer
Correct Answer: $x + y > z$
Explanation
### Concept & Logic
The transitive property of inequalities states that if $A > B$ and $B > C$, then $A > C$. Finding a common variable that bridges two inequalities is the key to determining a necessary truth.
### Step-by-Step Solution
1. Identify the given relations: $x > y + z$ (Equation 1), $x + y > p$ (Equation 2), and $z < p$ (Equation 3).
2. Rewrite Equation 3 so the inequality sign faces the same direction as Equation 2: $p > z$.
3. Analyze the relationship between Equation 2 and the rewritten Equation 3.
4. We have $x + y > p$ and $p > z$.
5. Applying the transitive property, we can chain these together: $x + y > p > z$.
6. This strictly implies that $x + y > z$.
7. The first relation ($x > y + z$) is extra information and is not required to prove this conclusion.
### Exam Strategy & Shortcut
Scan the inequalities for a "bridge" variable. Here, $p$ appears in two separate simple relations. Linking $x + y > p$ directly to $p > z$ gives you $x + y > z$ in seconds without any complex manipulation or number substitution.
### Common Pitfall
Getting distracted by the first equation ($x > y + z$) and attempting to add, subtract, or substitute all three equations together. This wastes time and can lead to mathematical dead-ends or incorrect assumptions.
### Final Answer
**Therefore, the correct answer is $x + y > z$.**