Finding the Fourth Proportional to 12,878.37, 17,772.39 and 7,842.78

Step by Step Solution

1. Step 1: Write the proportion equation
   12,878.37 : 17,772.39 = 7,842.78 : x
2. Step 2: Convert to fraction form
   12,878.37/17,772.39 = 7,842.78/x
3. Step 3: Cross multiply
   12,878.37x = 17,772.39 × 7,842.78
4. Step 4: Simplify right side
   12,878.37x = 139,384,944.84
5. Step 5: Solve for x
   x = 139,384,944.84/12,878.37
6. Step 6: Final answer
   x = 10,823.18