Finding the Fourth Proportional to 256,597.69, 384,856.10 and 85,818.10

Step by Step Solution

1. Step 1: Write the proportion equation
   256,597.69 : 384,856.10 = 85,818.10 : x
2. Step 2: Convert to fraction form
   256,597.69/384,856.10 = 85,818.10/x
3. Step 3: Cross multiply
   256,597.69x = 384,856.10 × 85,818.10
4. Step 4: Simplify right side
   256,597.69x = 33,027,619,275.41
5. Step 5: Solve for x
   x = 33,027,619,275.41/256,597.69
6. Step 6: Final answer
   x = 128,713.63