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GATE 2017 EC – Question 3

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 1 mark · Multiple choice

In the summer, water consumption is known to decrease overall by 25%. A Water Board official states that in the summer household consumption decreases by 20%, while other consumption increases by 70%.

Which of the following statements is correct?

  1. The ratio of household to other consumption is 8/17
  2. The ratio of household to other consumption is 1/17
  3. The ratio of household to other consumption is 17/8
  4. There are errors in the official's statement.

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Correct answer: (D) There are errors in the official's statement.

Explanation

Let household use be $h$ and other use be $o$. The new total is $0.8h + 1.7o$, and it must equal $0.75(h + o)$. That gives $0.05h + 0.95o = 0$, which cannot hold for positive $h$ and $o$. So the official's figures are inconsistent.