Finding the Fourth Proportional to 31,086.38, 42,886.36 and 21,660.42

Step by Step Solution

1. Step 1: Write the proportion equation
   31,086.38 : 42,886.36 = 21,660.42 : x
2. Step 2: Convert to fraction form
   31,086.38/42,886.36 = 21,660.42/x
3. Step 3: Cross multiply
   31,086.38x = 42,886.36 × 21,660.42
4. Step 4: Simplify right side
   31,086.38x = 928,936,569.87
5. Step 5: Solve for x
   x = 928,936,569.87/31,086.38
6. Step 6: Final answer
   x = 29,882.43