Finding the Fourth Proportional to 12,816.18, 17,680.05 and 9,978.54

Step by Step Solution

1. Step 1: Write the proportion equation
   12,816.18 : 17,680.05 = 9,978.54 : x
2. Step 2: Convert to fraction form
   12,816.18/17,680.05 = 9,978.54/x
3. Step 3: Cross multiply
   12,816.18x = 17,680.05 × 9,978.54
4. Step 4: Simplify right side
   12,816.18x = 176,421,086.13
5. Step 5: Solve for x
   x = 176,421,086.13/12,816.18
6. Step 6: Final answer
   x = 13,765.50