Finding the Fourth Proportional to 1,005.72, 1,387.83 and 612.66

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.72 : 1,387.83 = 612.66 : x
2. Step 2: Convert to fraction form
   1,005.72/1,387.83 = 612.66/x
3. Step 3: Cross multiply
   1,005.72x = 1,387.83 × 612.66
4. Step 4: Simplify right side
   1,005.72x = 850,267.93
5. Step 5: Solve for x
   x = 850,267.93/1,005.72
6. Step 6: Final answer
   x = 845.43