Finding the Fourth Proportional to 1,103.10, 1,687.10 and 1,103.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,103.10 : 1,687.10 = 1,103.10 : x
2. Step 2: Convert to fraction form
   1,103.10/1,687.10 = 1,103.10/x
3. Step 3: Cross multiply
   1,103.10x = 1,687.10 × 1,103.10
4. Step 4: Simplify right side
   1,103.10x = 1,861,034.49
5. Step 5: Solve for x
   x = 1,861,034.49/1,103.10
6. Step 6: Final answer
   x = 1,687.10