A random sample of 100 observations from a population gave $\sum(x - 50) = 123.5$ . What is the unbiased estimate of the population mean $\mu$ , to 3 decimal places?

Model answer

51.235

Explanation: The unbiased estimate of the mean is

\bar{x} = 50 + \frac{\sum(x-50)}{n} = 50 + \frac{123.5}{100} = 51.235

Derived from ZIMSEC Statistics Paper 2, November 2018, Q8

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