Finding the Fourth Proportional to 8,317.86, 12,478.65 and 3,123.78

Step by Step Solution

1. Step 1: Write the proportion equation
   8,317.86 : 12,478.65 = 3,123.78 : x
2. Step 2: Convert to fraction form
   8,317.86/12,478.65 = 3,123.78/x
3. Step 3: Cross multiply
   8,317.86x = 12,478.65 × 3,123.78
4. Step 4: Simplify right side
   8,317.86x = 38,980,557.30
5. Step 5: Solve for x
   x = 38,980,557.30/8,317.86
6. Step 6: Final answer
   x = 4,686.37