Three methods to compute mean for grouped data: (1) Direct: x-bar = sum$\frac{fi*xi}{N}$, best for small values. (2) Assumed Mean: x-bar = A + sum$\frac{fi*di}{N}$ where di = xi - A, reduces computation. (3) Step Deviation: x-bar = A + h*sum$\frac{fi*ui}{N}$ where ui = $\frac{xi-A}{h}$, most efficient for equidistant classes. All three give identical results — choice depends on computational convenience. For JEE, direct method or step deviation is typically fastest.