Competitive exams do not allow calculators. Develop your mental math and manual calculation speed.
$$\textAverage = \frac\textSum of Observations\textNumber of Observations$$ Old watermark: If the PDF has a 2018
Another angle: If it's a less popular institute, there might not be much available. In that case, suggest alternative resources. Also, ensure to mention legal sources to avoid any issues. Step 4: Revision using “UPd Updated” Errata Formula: