Finding the Fourth Proportional to 12,870.47, 19,220.05 and 12,731.30

Step by Step Solution

1. Step 1: Write the proportion equation
   12,870.47 : 19,220.05 = 12,731.30 : x
2. Step 2: Convert to fraction form
   12,870.47/19,220.05 = 12,731.30/x
3. Step 3: Cross multiply
   12,870.47x = 19,220.05 × 12,731.30
4. Step 4: Simplify right side
   12,870.47x = 244,696,222.57
5. Step 5: Solve for x
   x = 244,696,222.57/12,870.47
6. Step 6: Final answer
   x = 19,012.22