Finding the Fourth Proportional to 12,354.50, 18,531.78 and 3,120.50

Step by Step Solution

1. Step 1: Write the proportion equation
   12,354.50 : 18,531.78 = 3,120.50 : x
2. Step 2: Convert to fraction form
   12,354.50/18,531.78 = 3,120.50/x
3. Step 3: Cross multiply
   12,354.50x = 18,531.78 × 3,120.50
4. Step 4: Simplify right side
   12,354.50x = 57,828,419.49
5. Step 5: Solve for x
   x = 57,828,419.49/12,354.50
6. Step 6: Final answer
   x = 4,680.76