Finding the Fourth Proportional to 1,638.38, 2,458.35 and 816.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,638.38 : 2,458.35 = 816.72 : x
2. Step 2: Convert to fraction form
   1,638.38/2,458.35 = 816.72/x
3. Step 3: Cross multiply
   1,638.38x = 2,458.35 × 816.72
4. Step 4: Simplify right side
   1,638.38x = 2,007,783.61
5. Step 5: Solve for x
   x = 2,007,783.61/1,638.38
6. Step 6: Final answer
   x = 1,225.47