Finding the Fourth Proportional to 20,772.40, 31,165.89 and 12,972.10

Step by Step Solution

1. Step 1: Write the proportion equation
   20,772.40 : 31,165.89 = 12,972.10 : x
2. Step 2: Convert to fraction form
   20,772.40/31,165.89 = 12,972.10/x
3. Step 3: Cross multiply
   20,772.40x = 31,165.89 × 12,972.10
4. Step 4: Simplify right side
   20,772.40x = 404,287,041.67
5. Step 5: Solve for x
   x = 404,287,041.67/20,772.40
6. Step 6: Final answer
   x = 19,462.70