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CA Foundation · Quantitative Aptitude · Statistical Description of Data

A survey of 400 households in a city is planned. The city has three income zones with 2,000, 3,000 and 5,000 households respectively, and the sample is to be drawn from each zone in proportion to its size. How many households should be selected from the second zone, and which sampling method is this?

120 households should be selected from the second zone, and the method is proportionate stratified sampling. The second zone holds 3,000 of 10,000 households, so its share is 30% of 400, which is 120.

  1. A120 households; proportionate stratified samplingCorrect
  2. B133 households; simple random sampling
  3. C120 households; systematic sampling
  4. D100 households; cluster sampling

Explanation

Total households are 2,000+3,000+5,000 = 10,000. Second zone share = 3,000/10,000 × 400 = 120. Drawing from each group in proportion to its size is proportionate stratified sampling. Equal division would give 133, which ignores the proportions, and the other methods do not use strata allocation.

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