Give two examples each of sample, population and variable.
Population refers to the totality of items under study. Two examples are: (i) All students of Class XI for a study on textbook popularity, and (ii) All wheat farms in Punjab for estimating average yield.
A Sample is a section of the population from which information is obtained. Two examples are: (i) Ten years selected to analyze foodgrain production trends, and (ii) 50 farms surveyed in a village of 200 farms.
A Variable is a characteristic that can be measured. Two examples are: (i) Income of farmers, and (ii) Yield per hectare.
Explanation
The answer is derived directly from the activities and examples provided in the text. For Population, the text explicitly asks what the population would be for studying Class XI students and wheat yield in Punjab. For Sample, the text mentions selecting ten years for production analysis and surveying 50 farms. For Variable, the text explicitly identifies 'income of farmers' as a variable and lists 'yield per hectare' as a data point to be collected.