Finding the Fourth Proportional to 1,688.28, 2,328.55 and 1,128.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,688.28 : 2,328.55 = 1,128.57 : x
2. Step 2: Convert to fraction form
   1,688.28/2,328.55 = 1,128.57/x
3. Step 3: Cross multiply
   1,688.28x = 2,328.55 × 1,128.57
4. Step 4: Simplify right side
   1,688.28x = 2,627,931.67
5. Step 5: Solve for x
   x = 2,627,931.67/1,688.28
6. Step 6: Final answer
   x = 1,556.57