Finding the Fourth Proportional to 5,781.38, 7,978.32 and 3,128.78

Step by Step Solution

1. Step 1: Write the proportion equation
   5,781.38 : 7,978.32 = 3,128.78 : x
2. Step 2: Convert to fraction form
   5,781.38/7,978.32 = 3,128.78/x
3. Step 3: Cross multiply
   5,781.38x = 7,978.32 × 3,128.78
4. Step 4: Simplify right side
   5,781.38x = 24,962,428.00
5. Step 5: Solve for x
   x = 24,962,428.00/5,781.38
6. Step 6: Final answer
   x = 4,317.73