Finding the Fourth Proportional to 21,801.30, 30,081.18 and 12,842.70

Step by Step Solution

1. Step 1: Write the proportion equation
   21,801.30 : 30,081.18 = 12,842.70 : x
2. Step 2: Convert to fraction form
   21,801.30/30,081.18 = 12,842.70/x
3. Step 3: Cross multiply
   21,801.30x = 30,081.18 × 12,842.70
4. Step 4: Simplify right side
   21,801.30x = 386,323,570.39
5. Step 5: Solve for x
   x = 386,323,570.39/21,801.30
6. Step 6: Final answer
   x = 17,720.21