Finding the Fourth Proportional to 18,978.78, 28,456.49 and 13,062.85

Step by Step Solution

1. Step 1: Write the proportion equation
   18,978.78 : 28,456.49 = 13,062.85 : x
2. Step 2: Convert to fraction form
   18,978.78/28,456.49 = 13,062.85/x
3. Step 3: Cross multiply
   18,978.78x = 28,456.49 × 13,062.85
4. Step 4: Simplify right side
   18,978.78x = 371,722,821.91
5. Step 5: Solve for x
   x = 371,722,821.91/18,978.78
6. Step 6: Final answer
   x = 19,586.23