Question:

In a certain system, the quantities A and B are measured as \(8\pm 0.08\) and \(6\pm 0.06\) respectively. Let \(x=AB\), \(y=A+B\) and \(z=A-B\). The correct order of % error in \(x\), \(y\) and \(z\) is

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Percentage errors add for a product, while absolute errors add for a sum or a difference.
Updated On: Nov 12, 2026
  • \(x=y>z\)
  • \(x\lt z\lt y\)
  • \(z>x>y\)
  • \(x>z>y\)
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The Correct Option is C

Solution and Explanation

Step 1: Understanding the Concept
For a product, fractional errors add. For a sum or a difference, absolute errors add and then the percentage is taken on the result.

Step 2: Error in x = AB
\(\dfrac{\Delta A}{A}=\dfrac{0.08}{8}=1\%\) and \(\dfrac{\Delta B}{B}=\dfrac{0.06}{6}=1\%\)
So the error in \(x\) is \(1\%+1\%=2\%\).

Step 3: Error in y = A + B
\(y=14\) and \(\Delta y=0.08+0.06=0.14\)
% error in \(y=\dfrac{0.14}{14}\times100=1\%\)

Step 4: Error in z = A - B
\(z=2\) and \(\Delta z=0.14\)
% error in \(z=\dfrac{0.14}{2}\times100=7\%\)

Step 5: Compare the options
The errors are \(7\%>2\%>1\%\), that is \(z>x>y\).

Final Answer:
The percentage errors are in the order z > x > y. \[ \boxed{\text{(C) }z>x>y} \]
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