Finding the Fourth Proportional to 31,127.31, 42,969.60 and 21,086.25

Step by Step Solution

1. Step 1: Write the proportion equation
   31,127.31 : 42,969.60 = 21,086.25 : x
2. Step 2: Convert to fraction form
   31,127.31/42,969.60 = 21,086.25/x
3. Step 3: Cross multiply
   31,127.31x = 42,969.60 × 21,086.25
4. Step 4: Simplify right side
   31,127.31x = 906,067,566.86
5. Step 5: Solve for x
   x = 906,067,566.86/31,127.31
6. Step 6: Final answer
   x = 29,108.44