Finding the Fourth Proportional to 1,812.78, 2,498.65 and 1,215.07

Step by Step Solution

1. Step 1: Write the proportion equation
   1,812.78 : 2,498.65 = 1,215.07 : x
2. Step 2: Convert to fraction form
   1,812.78/2,498.65 = 1,215.07/x
3. Step 3: Cross multiply
   1,812.78x = 2,498.65 × 1,215.07
4. Step 4: Simplify right side
   1,812.78x = 3,036,025.37
5. Step 5: Solve for x
   x = 3,036,025.37/1,812.78
6. Step 6: Final answer
   x = 1,674.79