Finding the Fourth Proportional to 21,910.55, 30,234.80 and 12,958.43

Step by Step Solution

1. Step 1: Write the proportion equation
   21,910.55 : 30,234.80 = 12,958.43 : x
2. Step 2: Convert to fraction form
   21,910.55/30,234.80 = 12,958.43/x
3. Step 3: Cross multiply
   21,910.55x = 30,234.80 × 12,958.43
4. Step 4: Simplify right side
   21,910.55x = 391,795,420.59
5. Step 5: Solve for x
   x = 391,795,420.59/21,910.55
6. Step 6: Final answer
   x = 17,881.59