Finding the Fourth Proportional to 20,780.15, 31,177.51 and 10,780.09

Step by Step Solution

1. Step 1: Write the proportion equation
   20,780.15 : 31,177.51 = 10,780.09 : x
2. Step 2: Convert to fraction form
   20,780.15/31,177.51 = 10,780.09/x
3. Step 3: Cross multiply
   20,780.15x = 31,177.51 × 10,780.09
4. Step 4: Simplify right side
   20,780.15x = 336,096,258.88
5. Step 5: Solve for x
   x = 336,096,258.88/20,780.15
6. Step 6: Final answer
   x = 16,173.91