Finding the Fourth Proportional to 20,395.61, 28,155.83 and 13,678.78

Step by Step Solution

1. Step 1: Write the proportion equation
   20,395.61 : 28,155.83 = 13,678.78 : x
2. Step 2: Convert to fraction form
   20,395.61/28,155.83 = 13,678.78/x
3. Step 3: Cross multiply
   20,395.61x = 28,155.83 × 13,678.78
4. Step 4: Simplify right side
   20,395.61x = 385,137,404.29
5. Step 5: Solve for x
   x = 385,137,404.29/20,395.61
6. Step 6: Final answer
   x = 18,883.35