Finding the Fourth Proportional to 9,321.30, 12,861.86 and 5,129.55

Step by Step Solution

1. Step 1: Write the proportion equation
   9,321.30 : 12,861.86 = 5,129.55 : x
2. Step 2: Convert to fraction form
   9,321.30/12,861.86 = 5,129.55/x
3. Step 3: Cross multiply
   9,321.30x = 12,861.86 × 5,129.55
4. Step 4: Simplify right side
   9,321.30x = 65,975,528.32
5. Step 5: Solve for x
   x = 65,975,528.32/9,321.30
6. Step 6: Final answer
   x = 7,077.93