Finding the Fourth Proportional to 7,091.78, 10,621.83 and 5,139.50

Step by Step Solution

1. Step 1: Write the proportion equation
   7,091.78 : 10,621.83 = 5,139.50 : x
2. Step 2: Convert to fraction form
   7,091.78/10,621.83 = 5,139.50/x
3. Step 3: Cross multiply
   7,091.78x = 10,621.83 × 5,139.50
4. Step 4: Simplify right side
   7,091.78x = 54,590,895.29
5. Step 5: Solve for x
   x = 54,590,895.29/7,091.78
6. Step 6: Final answer
   x = 7,697.77