Finding the Fourth Proportional to 8,985.83, 12,400.56 and 5,209.20

Step by Step Solution

1. Step 1: Write the proportion equation
   8,985.83 : 12,400.56 = 5,209.20 : x
2. Step 2: Convert to fraction form
   8,985.83/12,400.56 = 5,209.20/x
3. Step 3: Cross multiply
   8,985.83x = 12,400.56 × 5,209.20
4. Step 4: Simplify right side
   8,985.83x = 64,596,997.15
5. Step 5: Solve for x
   x = 64,596,997.15/8,985.83
6. Step 6: Final answer
   x = 7,188.77