Finding the Fourth Proportional to 20,921.34, 28,864.50 and 12,426.06

Step by Step Solution

1. Step 1: Write the proportion equation
   20,921.34 : 28,864.50 = 12,426.06 : x
2. Step 2: Convert to fraction form
   20,921.34/28,864.50 = 12,426.06/x
3. Step 3: Cross multiply
   20,921.34x = 28,864.50 × 12,426.06
4. Step 4: Simplify right side
   20,921.34x = 358,672,008.87
5. Step 5: Solve for x
   x = 358,672,008.87/20,921.34
6. Step 6: Final answer
   x = 17,143.84