Finding the Fourth Proportional to 12,456.86, 17,181.92 and 7,978.64

Step by Step Solution

1. Step 1: Write the proportion equation
   12,456.86 : 17,181.92 = 7,978.64 : x
2. Step 2: Convert to fraction form
   12,456.86/17,181.92 = 7,978.64/x
3. Step 3: Cross multiply
   12,456.86x = 17,181.92 × 7,978.64
4. Step 4: Simplify right side
   12,456.86x = 137,088,288.23
5. Step 5: Solve for x
   x = 137,088,288.23/12,456.86
6. Step 6: Final answer
   x = 11,005.05