Finding the Fourth Proportional to 9,861.80, 13,608.89 and 5,385.55

Step by Step Solution

1. Step 1: Write the proportion equation
   9,861.80 : 13,608.89 = 5,385.55 : x
2. Step 2: Convert to fraction form
   9,861.80/13,608.89 = 5,385.55/x
3. Step 3: Cross multiply
   9,861.80x = 13,608.89 × 5,385.55
4. Step 4: Simplify right side
   9,861.80x = 73,291,262.57
5. Step 5: Solve for x
   x = 73,291,262.57/9,861.80
6. Step 6: Final answer
   x = 7,431.83