Finding the Fourth Proportional to 5,781.60, 7,978.56 and 3,128.98

Step by Step Solution

1. Step 1: Write the proportion equation
   5,781.60 : 7,978.56 = 3,128.98 : x
2. Step 2: Convert to fraction form
   5,781.60/7,978.56 = 3,128.98/x
3. Step 3: Cross multiply
   5,781.60x = 7,978.56 × 3,128.98
4. Step 4: Simplify right side
   5,781.60x = 24,964,754.67
5. Step 5: Solve for x
   x = 24,964,754.67/5,781.60
6. Step 6: Final answer
   x = 4,317.97