Finding the Fourth Proportional to 31,147.89, 42,979.02 and 18,399.31

Step by Step Solution

1. Step 1: Write the proportion equation
   31,147.89 : 42,979.02 = 18,399.31 : x
2. Step 2: Convert to fraction form
   31,147.89/42,979.02 = 18,399.31/x
3. Step 3: Cross multiply
   31,147.89x = 42,979.02 × 18,399.31
4. Step 4: Simplify right side
   31,147.89x = 790,784,312.48
5. Step 5: Solve for x
   x = 790,784,312.48/31,147.89
6. Step 6: Final answer
   x = 25,388.05