Finding the Fourth Proportional to 21,469.78, 29,628.60 and 12,970.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,469.78 : 29,628.60 = 12,970.72 : x
2. Step 2: Convert to fraction form
   21,469.78/29,628.60 = 12,970.72/x
3. Step 3: Cross multiply
   21,469.78x = 29,628.60 × 12,970.72
4. Step 4: Simplify right side
   21,469.78x = 384,304,200.52
5. Step 5: Solve for x
   x = 384,304,200.52/21,469.78
6. Step 6: Final answer
   x = 17,899.78