Finding the Fourth Proportional to 21,789.70, 30,071.82 and 12,839.98

Step by Step Solution

1. Step 1: Write the proportion equation
   21,789.70 : 30,071.82 = 12,839.98 : x
2. Step 2: Convert to fraction form
   21,789.70/30,071.82 = 12,839.98/x
3. Step 3: Cross multiply
   21,789.70x = 30,071.82 × 12,839.98
4. Step 4: Simplify right side
   21,789.70x = 386,121,567.36
5. Step 5: Solve for x
   x = 386,121,567.36/21,789.70
6. Step 6: Final answer
   x = 17,720.37