Finding the Fourth Proportional to 30,881.89, 42,620.78 and 20,138.25

Step by Step Solution

1. Step 1: Write the proportion equation
   30,881.89 : 42,620.78 = 20,138.25 : x
2. Step 2: Convert to fraction form
   30,881.89/42,620.78 = 20,138.25/x
3. Step 3: Cross multiply
   30,881.89x = 42,620.78 × 20,138.25
4. Step 4: Simplify right side
   30,881.89x = 858,308,133.01
5. Step 5: Solve for x
   x = 858,308,133.01/30,881.89
6. Step 6: Final answer
   x = 27,793.25