Q.The true average monthly sales of all 400 outlets in a district is known (from complete records) to be ₹50,000. A sample of 40 outlets, selected for a quick survey, gives a sample mean of ₹47,000. Compute the sampling error, and state whether this error would also be present if a complete census of all 400 outlets had been conducted instead.

Sampling error measures how far a sample-based estimate falls from the true population value.

Given: true population mean $\mu = ₹50{,}000$; sample mean $\bar{x} = ₹47{,}000$.

Sampling Error $= |\bar{x} - \mu| = |47{,}000 - 50{,}000| = ₹3{,}000$.

Verification (independent check): since $\bar{x} < \mu$ here, the sample happened to understate the true average; recomputing as $\mu - \bar{x} = 50{,}000 - 47{,}000 = 3{,}000$ confirms the same magnitude regardless of the order of subtraction, since sampling error is always reported as an absolute value. …

Reporting a negative error by not taking the absolute difference, or wrongly assuming a census would also have some 'sampling error' si …