Q.Define population and sample. Illustrate with one example from a business context.

In Statistics, every enquiry begins by fixing exactly who or what is being studied, and how much of it will actually be examined.

Population (Universe) is the complete, well-defined set of all individuals, items, or observations about which information is sought. It can be finite (all shops registered in a taluka) or very large (all transactions on a payment app in a year).

Sample is a smaller, representative part of the population, actually selected and studied, from which conclusions about the whole population are drawn. A sample is useful only if it genuinely represents the population it comes from.

Business example: A company wants to estimate the average monthly spending of its 20,000 registered customers. All 20,000 customers together form the population. Since surveying every customer would be costly and slow, the company instead selects 500 customers to survey; these 500 customers form the sample, and the results from them are used to estimate the spending pattern of all 20,000.

Students often confuse 'sample' with 'sample size' (the number of units selected, not the units themselves), and sometimes describe an unrepresentative, casually chosen group as a valid 'sample' even though it does not reflect the population.