Finding the Fourth Proportional to 31,078.72, 42,874.98 and 21,003.49

Step by Step Solution

1. Step 1: Write the proportion equation
   31,078.72 : 42,874.98 = 21,003.49 : x
2. Step 2: Convert to fraction form
   31,078.72/42,874.98 = 21,003.49/x
3. Step 3: Cross multiply
   31,078.72x = 42,874.98 × 21,003.49
4. Step 4: Simplify right side
   31,078.72x = 900,524,213.68
5. Step 5: Solve for x
   x = 900,524,213.68/31,078.72
6. Step 6: Final answer
   x = 28,975.59