Finding the Fourth Proportional to 10,860.32, 14,978.30 and 9,129.08

Step by Step Solution

1. Step 1: Write the proportion equation
   10,860.32 : 14,978.30 = 9,129.08 : x
2. Step 2: Convert to fraction form
   10,860.32/14,978.30 = 9,129.08/x
3. Step 3: Cross multiply
   10,860.32x = 14,978.30 × 9,129.08
4. Step 4: Simplify right side
   10,860.32x = 136,738,098.96
5. Step 5: Solve for x
   x = 136,738,098.96/10,860.32
6. Step 6: Final answer
   x = 12,590.61