Finding the Fourth Proportional to 2,600.78, 3,900.47 and 1,212.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,600.78 : 3,900.47 = 1,212.76 : x
2. Step 2: Convert to fraction form
   2,600.78/3,900.47 = 1,212.76/x
3. Step 3: Cross multiply
   2,600.78x = 3,900.47 × 1,212.76
4. Step 4: Simplify right side
   2,600.78x = 4,730,334.00
5. Step 5: Solve for x
   x = 4,730,334.00/2,600.78
6. Step 6: Final answer
   x = 1,818.81