Finding the Fourth Proportional to 1,189.54, 1,641.42 and 665.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.54 : 1,641.42 = 665.50 : x
2. Step 2: Convert to fraction form
   1,189.54/1,641.42 = 665.50/x
3. Step 3: Cross multiply
   1,189.54x = 1,641.42 × 665.50
4. Step 4: Simplify right side
   1,189.54x = 1,092,365.01
5. Step 5: Solve for x
   x = 1,092,365.01/1,189.54
6. Step 6: Final answer
   x = 918.31