| Exam Board | OCR |
|---|---|
| Module | S2 (Statistics 2) |
| Year | 2010 |
| Session | January |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Measures of Location and Spread |
| Type | Standard unbiased estimates calculation |
| Difficulty | Easy -1.2 This is a straightforward application of standard formulas for unbiased estimates of mean and variance given summary statistics. It requires only direct substitution into well-known formulas (x̄ = Σx/n and s² = [Σx² - (Σx)²/n]/(n-1)) with minimal calculation, making it easier than average and purely procedural with no problem-solving element. |
| Spec | 5.05b Unbiased estimates: of population mean and variance |
The values of 5 independent observations from a population can be summarised by
$$\sum x = 75.8, \quad \sum x^2 = 1154.58.$$
Find unbiased estimates of the population mean and variance. [4]
\hfill \mbox{\textit{OCR S2 2010 Q1 [4]}}