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Decision rule for hypothesis testing:
- If \(p \leq \alpha\): Reject the null hypothesis \((H_0)\)
- If \(p > \alpha\): Fail to reject the null hypothesis
Important note: Statistical significance does not automatically mean clinical significance. A nurse must also evaluate effect size and practical relevance. Saying 'accept the null hypothesis' is incorrect terminology in research — we only ever reject or fail to reject it.
Five observations have mean $= 4$ and variance $= 5.2$. Three of the observations are $3, 4, 4$. Find the absolute difference between the remaining two observations.
Step 1 — Find the sum: $\sum x_i = 5\times4=20$. Known three: $3+4+4=11$. So $x_4+x_5=9$.
Step 2 — Find sum of squares: Variance $=\frac{\sum x_i^2}{n}-\bar{x}^2 \Rightarrow \frac{\sum x_i^2}{5}-16=5.2 \Rightarrow \sum x_i^2=106$.
Known: $3^2+4^2+4^2=9+16+16=41$. So $x_4^2+x_5^2=65$.
Step 3 — Solve: $x_4+x_5=9$ and $x_4^2+x_5^2=65$.
$(x_4+x_5)^2=81 \Rightarrow 2x_4x_5=81-65=16 \Rightarrow x_4x_5=8$.
$(x_4-x_5)^2=(x_4+x_5)^2-4x_4x_5=81-32=49$
$|x_4-x_5|=\mathbf{7}$
The IFJ Declaration of Principles (adopted 1954, amended 1986 in Helsingör) specifically defines the following as grave professional offences for journalists:
- Plagiarism
- Malicious misrepresentation
- Calumny, slander, libel, and unfounded accusations
- Acceptance of a bribe in any form in consideration of either publication or suppression of information
Expressing personal political opinions in editorial content is not listed as a grave professional offence in this declaration. The declaration also requires journalists to: respect truth, defend freedom of information, report only facts of known origin, use only fair methods to obtain news, rectify inaccurate information, observe professional secrecy regarding sources, and be aware of discrimination. The code emphasises that journalists should recognise “in professional matters the jurisdiction of colleagues only, to the exclusion of every kind of interference by governments or others.”
- Initial $[H^{+}] = 10^{-1} = 0.1 \text{ M}$.
- Final $[H^{+}] = 10^{-2} = 0.01 \text{ M}$.
- Using dilution formula $M_{1}V_{1} = M_{2}V_{2}$:
- $0.1 \times 1 = 0.01 \times V_{2} \implies V_{2} = 10 \text{ L}$.
- Volume to be added = $V_{2} - V_{1} = 10 - 1 = 9 \text{ L}$.
- Heat (temperature): drives recrystallisation and mineral reactions; increases with burial depth and proximity to magma
- Pressure: confining pressure (lithostatic) increases with depth; directed pressure (stress) causes foliation and lineation
- Chemically active fluids: water, CO₂, and dissolved ions catalyse mineral reactions, enable mass transfer, and are essential for many metamorphic reactions
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