Finding the Fourth Proportional to 1,216.83, 1,678.72 and 898.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.83 : 1,678.72 = 898.55 : x
2. Step 2: Convert to fraction form
   1,216.83/1,678.72 = 898.55/x
3. Step 3: Cross multiply
   1,216.83x = 1,678.72 × 898.55
4. Step 4: Simplify right side
   1,216.83x = 1,508,418.11
5. Step 5: Solve for x
   x = 1,508,418.11/1,216.83
6. Step 6: Final answer
   x = 1,239.63