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NDA 1 2024 Maths, question 107

Topic: Statistics

Q107

An edible oil is sold at the rates 150,200,250,300150,200,250,300 rupees per litre in four consecutive years. Assuming that an equal amount of money is spent on oil by a family in every year during these years, what is the average price of oil in rupees (approximately) per litre ?

  1. (a) 210210Correct answer
  2. (b) 220220
  3. (c) 230230
  4. (d) 240240

Solution.

Answer: (a) 210210

  1. Equal expenditure requires the harmonic mean of the four prices: 4/(1/150 + 1/200 + 1/250 + 1/300) = 4/(19/1000) = 4000/19 ≈ 210.53 rupees per litre.
  2. The closest listed value is 210.