1. The equation of the hyperbola is:
\[ \frac{x^2}{4} - \frac{y^2}{9} = 1. \]
2. The equation of the chord parallel to \(y = 2x\) is:
\[ y = 2x + c. \]
3. Using the midpoint formula for a hyperbola: - The midpoint satisfies the locus equation derived from substituting \(y = 2x + c\) into the hyperbola equation.
4. After simplification, the locus of the midpoint is:
\[ 9x - 8y = 0. \]

A quantity \( X \) is given by: \[ X = \frac{\epsilon_0 L \Delta V}{\Delta t} \] where:
- \( \epsilon_0 \) is the permittivity of free space,
- \( L \) is the length,
- \( \Delta V \) is the potential difference,
- \( \Delta t \) is the time interval.
The dimension of \( X \) is the same as that of: