Finding the Fourth Proportional to 1,166.72, 1,610.07 and 642.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,166.72 : 1,610.07 = 642.75 : x
2. Step 2: Convert to fraction form
   1,166.72/1,610.07 = 642.75/x
3. Step 3: Cross multiply
   1,166.72x = 1,610.07 × 642.75
4. Step 4: Simplify right side
   1,166.72x = 1,034,872.49
5. Step 5: Solve for x
   x = 1,034,872.49/1,166.72
6. Step 6: Final answer
   x = 886.99