Finding the Fourth Proportional to 20,740.25, 31,118.18 and 12,426.21

Step by Step Solution

1. Step 1: Write the proportion equation
   20,740.25 : 31,118.18 = 12,426.21 : x
2. Step 2: Convert to fraction form
   20,740.25/31,118.18 = 12,426.21/x
3. Step 3: Cross multiply
   20,740.25x = 31,118.18 × 12,426.21
4. Step 4: Simplify right side
   20,740.25x = 386,680,977.37
5. Step 5: Solve for x
   x = 386,680,977.37/20,740.25
6. Step 6: Final answer
   x = 18,643.99