Finding the Fourth Proportional to 21,356.37, 31,815.72 and 21,123.09

Step by Step Solution

1. Step 1: Write the proportion equation
   21,356.37 : 31,815.72 = 21,123.09 : x
2. Step 2: Convert to fraction form
   21,356.37/31,815.72 = 21,123.09/x
3. Step 3: Cross multiply
   21,356.37x = 31,815.72 × 21,123.09
4. Step 4: Simplify right side
   21,356.37x = 672,046,316.97
5. Step 5: Solve for x
   x = 672,046,316.97/21,356.37
6. Step 6: Final answer
   x = 31,468.19