Finding the Fourth Proportional to 1,166.58, 1,609.89 and 642.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,166.58 : 1,609.89 = 642.60 : x
2. Step 2: Convert to fraction form
   1,166.58/1,609.89 = 642.60/x
3. Step 3: Cross multiply
   1,166.58x = 1,609.89 × 642.60
4. Step 4: Simplify right side
   1,166.58x = 1,034,515.31
5. Step 5: Solve for x
   x = 1,034,515.31/1,166.58
6. Step 6: Final answer
   x = 886.79