Finding the Fourth Proportional to 21,780.72, 30,062.30 and 13,285.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,780.72 : 30,062.30 = 13,285.72 : x
2. Step 2: Convert to fraction form
   21,780.72/30,062.30 = 13,285.72/x
3. Step 3: Cross multiply
   21,780.72x = 30,062.30 × 13,285.72
4. Step 4: Simplify right side
   21,780.72x = 399,399,300.36
5. Step 5: Solve for x
   x = 399,399,300.36/21,780.72
6. Step 6: Final answer
   x = 18,337.29