Finding the Fourth Proportional to 1,015.59, 1,401.51 and 642.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,015.59 : 1,401.51 = 642.73 : x
2. Step 2: Convert to fraction form
   1,015.59/1,401.51 = 642.73/x
3. Step 3: Cross multiply
   1,015.59x = 1,401.51 × 642.73
4. Step 4: Simplify right side
   1,015.59x = 900,789.31
5. Step 5: Solve for x
   x = 900,789.31/1,015.59
6. Step 6: Final answer
   x = 886.96