GCSE Maths Formulas

\( \bar{x}=\tfrac{n_1\bar{x}_1+n_2\bar{x}_2}{n_1+n_2} \)

\( \text{Median}=L+\frac{\tfrac{N}{2}-\text{CF}}{f}\times w \)

\( Q_k\ \text{or}\ P_p= L+\frac{kN-\text{CF}}{f}\times w \)

\( \text{Frequency Density}=\frac{\text{Frequency}}{\text{Class Width}} \)

\( IQR=Q_3-Q_1 \)

\( \bar{x}=\frac{\sum f x}{\sum f} \)

\( x_{\text{mid}}=\tfrac{\text{lower boundary}+\text{upper boundary}}{2} \)

\( Q_1\text{ near }\tfrac{N+1}{4},\quad \text{Median near }\tfrac{N+1}{2},\quad Q_3\text{ near }\tfrac{3(N+1)}{4} \)