Finding the Fourth Proportional to 1,105.63, 1,658.79 and 642.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,105.63 : 1,658.79 = 642.43 : x
2. Step 2: Convert to fraction form
   1,105.63/1,658.79 = 642.43/x
3. Step 3: Cross multiply
   1,105.63x = 1,658.79 × 642.43
4. Step 4: Simplify right side
   1,105.63x = 1,065,657.40
5. Step 5: Solve for x
   x = 1,065,657.40/1,105.63
6. Step 6: Final answer
   x = 963.85