Finding the Fourth Proportional to 12,986.78, 17,915 and 7,672.38

Step by Step Solution

1. Step 1: Write the proportion equation
   12,986.78 : 17,915 = 7,672.38 : x
2. Step 2: Convert to fraction form
   12,986.78/17,915 = 7,672.38/x
3. Step 3: Cross multiply
   12,986.78x = 17,915 × 7,672.38
4. Step 4: Simplify right side
   12,986.78x = 137,450,687.70
5. Step 5: Solve for x
   x = 137,450,687.70/12,986.78
6. Step 6: Final answer
   x = 10,583.89