Finding the Fourth Proportional to 21,870.58, 30,180.52 and 12,920.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,870.58 : 30,180.52 = 12,920.96 : x
2. Step 2: Convert to fraction form
   21,870.58/30,180.52 = 12,920.96/x
3. Step 3: Cross multiply
   21,870.58x = 30,180.52 × 12,920.96
4. Step 4: Simplify right side
   21,870.58x = 389,961,291.70
5. Step 5: Solve for x
   x = 389,961,291.70/21,870.58
6. Step 6: Final answer
   x = 17,830.40