Finding the Fourth Proportional to 278,892.10, 391,498.70 and 278,892.10

Step by Step Solution

1. Step 1: Write the proportion equation
   278,892.10 : 391,498.70 = 278,892.10 : x
2. Step 2: Convert to fraction form
   278,892.10/391,498.70 = 278,892.10/x
3. Step 3: Cross multiply
   278,892.10x = 391,498.70 × 278,892.10
4. Step 4: Simplify right side
   278,892.10x = 109,185,894,590.27
5. Step 5: Solve for x
   x = 109,185,894,590.27/278,892.10
6. Step 6: Final answer
   x = 391,498.70