Finding the Third Proportional to 258,615 and 398,824.50

Step by Step Solution

1. Step 1: Write the proportion equation
   258,615 : 398,824.50 = 398,824.50 : x
2. Step 2: Convert to fraction form
   258,615/398,824.50 = 398,824.50/x
3. Step 3: Cross multiply
   258,615x = 398,824.50 × 398,824.50
4. Step 4: Simplify right side
   258,615x = 159,060,981,800.25
5. Step 5: Solve for x
   x = 159,060,981,800.25/258,615
6. Step 6: Final answer
   x = 615,049.33