Finding the Fourth Proportional to 1,128.28, 1,691.98 and 397.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.28 : 1,691.98 = 397.72 : x
2. Step 2: Convert to fraction form
   1,128.28/1,691.98 = 397.72/x
3. Step 3: Cross multiply
   1,128.28x = 1,691.98 × 397.72
4. Step 4: Simplify right side
   1,128.28x = 672,934.29
5. Step 5: Solve for x
   x = 672,934.29/1,128.28
6. Step 6: Final answer
   x = 596.42