Finding the Fourth Proportional to 1,681.98, 2,519.72 and 816.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,681.98 : 2,519.72 = 816.90 : x
2. Step 2: Convert to fraction form
   1,681.98/2,519.72 = 816.90/x
3. Step 3: Cross multiply
   1,681.98x = 2,519.72 × 816.90
4. Step 4: Simplify right side
   1,681.98x = 2,058,359.27
5. Step 5: Solve for x
   x = 2,058,359.27/1,681.98
6. Step 6: Final answer
   x = 1,223.77