Finding the Fourth Proportional to 8,620.64, 12,931 and 3,426.50

Step by Step Solution

1. Step 1: Write the proportion equation
   8,620.64 : 12,931 = 3,426.50 : x
2. Step 2: Convert to fraction form
   8,620.64/12,931 = 3,426.50/x
3. Step 3: Cross multiply
   8,620.64x = 12,931 × 3,426.50
4. Step 4: Simplify right side
   8,620.64x = 44,308,071.50
5. Step 5: Solve for x
   x = 44,308,071.50/8,620.64
6. Step 6: Final answer
   x = 5,139.77