Finding the Fourth Proportional to 13,687.31, 18,888.46 and 7,399.69

Step by Step Solution

1. Step 1: Write the proportion equation
   13,687.31 : 18,888.46 = 7,399.69 : x
2. Step 2: Convert to fraction form
   13,687.31/18,888.46 = 7,399.69/x
3. Step 3: Cross multiply
   13,687.31x = 18,888.46 × 7,399.69
4. Step 4: Simplify right side
   13,687.31x = 139,768,682.86
5. Step 5: Solve for x
   x = 139,768,682.86/13,687.31
6. Step 6: Final answer
   x = 10,211.55