Finding the Fourth Proportional to 31,160.72, 42,987.24 and 21,086

Step by Step Solution

1. Step 1: Write the proportion equation
   31,160.72 : 42,987.24 = 21,086 : x
2. Step 2: Convert to fraction form
   31,160.72/42,987.24 = 21,086/x
3. Step 3: Cross multiply
   31,160.72x = 42,987.24 × 21,086
4. Step 4: Simplify right side
   31,160.72x = 906,428,942.64
5. Step 5: Solve for x
   x = 906,428,942.64/31,160.72
6. Step 6: Final answer
   x = 29,088.83