Finding the Fourth Proportional to 12,609.72, 18,886.42 and 9,139

Step by Step Solution

1. Step 1: Write the proportion equation
   12,609.72 : 18,886.42 = 9,139 : x
2. Step 2: Convert to fraction form
   12,609.72/18,886.42 = 9,139/x
3. Step 3: Cross multiply
   12,609.72x = 18,886.42 × 9,139
4. Step 4: Simplify right side
   12,609.72x = 172,602,992.38
5. Step 5: Solve for x
   x = 172,602,992.38/12,609.72
6. Step 6: Final answer
   x = 13,688.09