Finding the Fourth Proportional to 1,272.10, 1,904.55 and 1,128.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,272.10 : 1,904.55 = 1,128.10 : x
2. Step 2: Convert to fraction form
   1,272.10/1,904.55 = 1,128.10/x
3. Step 3: Cross multiply
   1,272.10x = 1,904.55 × 1,128.10
4. Step 4: Simplify right side
   1,272.10x = 2,148,522.86
5. Step 5: Solve for x
   x = 2,148,522.86/1,272.10
6. Step 6: Final answer
   x = 1,688.96