In the figure, each inside square is formed by joining the midpoints of the sides of the next larger square. The area of the smallest shaded square is to be found. The outermost square has a side length of 10 cm. 
Step 1: Area of the outermost square.
Side = 10 cm → Area = \(10^2 = 100\) cm².
Step 2: Area ratio for midpoint-joined squares.
Each new square = \( \frac{1}{2} \) × area of previous square.
Thus areas form the sequence:
\[
100,\; 50,\; 25,\; 12.5,\; 6.25,\; 3.125,\; \dots
\]
Step 3: Identify the smallest shaded square.
According to the diagram, the smallest (innermost) shaded square corresponds to
\[
100 \times \left(\frac{1}{2}\right)^5 = 3.125.
\]
Final Answer: 3.125

Given an open-loop transfer function \(GH = \frac{100}{s}(s+100)\) for a unity feedback system with a unit step input \(r(t)=u(t)\), determine the rise time \(t_r\).
Consider a linear time-invariant system represented by the state-space equation: \[ \dot{x} = \begin{bmatrix} a & b -a & 0 \end{bmatrix} x + \begin{bmatrix} 1 0 \end{bmatrix} u \] The closed-loop poles of the system are located at \(-2 \pm j3\). The value of the parameter \(b\) is: