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CA Foundation · Quantitative Aptitude · Statistical Description of Data

A bank in Jaipur has 1,000 account holders: 600 salaried, 300 self-employed and 100 retired. It selects a sample of 50 so that each group is represented in proportion to its size, and then picks randomly within each group. How many self-employed account holders will be in the sample, and what is this method called?

The sample has 15 self-employed account holders, found as 30% of 50, and the method is stratified random sampling. The population is split into groups, and each group is sampled randomly in proportion to its size, giving 30 salaried, 15 self-employed and 5 retired.

  1. A15 self-employed; stratified random samplingCorrect
  2. B15 self-employed; systematic sampling
  3. C30 self-employed; stratified random sampling
  4. D17 self-employed; simple random sampling

Explanation

Self-employed share = 300/1000 = 30%, so the sample has 0.30 × 50 = 15. Checking: salaried 30 + self-employed 15 + retired 5 = 50. Dividing the population into groups and sampling randomly within each in proportion is stratified random sampling. Systematic sampling picks every k-th unit, which is not used here. The 30 option mistakes the salaried group's count.

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