Finding the Fourth Proportional to 7,320.90, 10,992.15 and 5,139.30

Step by Step Solution

1. Step 1: Write the proportion equation
   7,320.90 : 10,992.15 = 5,139.30 : x
2. Step 2: Convert to fraction form
   7,320.90/10,992.15 = 5,139.30/x
3. Step 3: Cross multiply
   7,320.90x = 10,992.15 × 5,139.30
4. Step 4: Simplify right side
   7,320.90x = 56,491,956.50
5. Step 5: Solve for x
   x = 56,491,956.50/7,320.90
6. Step 6: Final answer
   x = 7,716.53