Finding the Fourth Proportional to 12,819.78, 17,691.42 and 7,230.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,819.78 : 17,691.42 = 7,230.78 : x
2. Step 2: Convert to fraction form
   12,819.78/17,691.42 = 7,230.78/x
3. Step 3: Cross multiply
   12,819.78x = 17,691.42 × 7,230.78
4. Step 4: Simplify right side
   12,819.78x = 127,922,765.91
5. Step 5: Solve for x
   x = 127,922,765.91/12,819.78
6. Step 6: Final answer
   x = 9,978.55