Finding the Fourth Proportional to 1,166.55, 1,609.82 and 642.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,166.55 : 1,609.82 = 642.57 : x
2. Step 2: Convert to fraction form
   1,166.55/1,609.82 = 642.57/x
3. Step 3: Cross multiply
   1,166.55x = 1,609.82 × 642.57
4. Step 4: Simplify right side
   1,166.55x = 1,034,422.04
5. Step 5: Solve for x
   x = 1,034,422.04/1,166.55
6. Step 6: Final answer
   x = 886.74