Finding the Fourth Proportional to 1,638.69, 2,456.55 and 816.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,638.69 : 2,456.55 = 816.54 : x
2. Step 2: Convert to fraction form
   1,638.69/2,456.55 = 816.54/x
3. Step 3: Cross multiply
   1,638.69x = 2,456.55 × 816.54
4. Step 4: Simplify right side
   1,638.69x = 2,005,871.34
5. Step 5: Solve for x
   x = 2,005,871.34/1,638.69
6. Step 6: Final answer
   x = 1,224.07