Finding the Fourth Proportional to 13,688.80, 18,890.56 and 7,401.18

Step by Step Solution

1. Step 1: Write the proportion equation
   13,688.80 : 18,890.56 = 7,401.18 : x
2. Step 2: Convert to fraction form
   13,688.80/18,890.56 = 7,401.18/x
3. Step 3: Cross multiply
   13,688.80x = 18,890.56 × 7,401.18
4. Step 4: Simplify right side
   13,688.80x = 139,812,434.86
5. Step 5: Solve for x
   x = 139,812,434.86/13,688.80
6. Step 6: Final answer
   x = 10,213.64