Finding the Fourth Proportional to 12,890.39, 17,787.15 and 7,852.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,890.39 : 17,787.15 = 7,852.78 : x
2. Step 2: Convert to fraction form
   12,890.39/17,787.15 = 7,852.78/x
3. Step 3: Cross multiply
   12,890.39x = 17,787.15 × 7,852.78
4. Step 4: Simplify right side
   12,890.39x = 139,678,627.46
5. Step 5: Solve for x
   x = 139,678,627.46/12,890.39
6. Step 6: Final answer
   x = 10,835.87