Q1. Calculate $x_i, choose assumed mean $a, $u_i = (x_i-a)/h. Formula: $\text{Mean} = a + h \frac{\sum f_i u_i}{\sum f_i}$.
Q2. Using cumulative frequency, locate median class. Equations for $x$ and $y$ yield $x = 9, y = 15$.
Q3. Locate modal class (highest frequency). Formula: $\text{Mode} = l + h \frac{f_1 - f_0}{2f_1 - f_0 - f_2}$.
Q4. Plot cumulative frequencies against upper limits of class intervals to draw the rising ogive curve.
Q5. Empirical relationship: $\text{Mode} = 3\text{ Median} - 2\text{ Mean}$.
