Finding the Fourth Proportional to 1,128.42, 1,691.23 and 511.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.42 : 1,691.23 = 511.50 : x
2. Step 2: Convert to fraction form
   1,128.42/1,691.23 = 511.50/x
3. Step 3: Cross multiply
   1,128.42x = 1,691.23 × 511.50
4. Step 4: Simplify right side
   1,128.42x = 865,064.15
5. Step 5: Solve for x
   x = 865,064.15/1,128.42
6. Step 6: Final answer
   x = 766.62