Finding the Fourth Proportional to 1,189.54, 1,641.72 and 665.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.54 : 1,641.72 = 665.56 : x
2. Step 2: Convert to fraction form
   1,189.54/1,641.72 = 665.56/x
3. Step 3: Cross multiply
   1,189.54x = 1,641.72 × 665.56
4. Step 4: Simplify right side
   1,189.54x = 1,092,663.16
5. Step 5: Solve for x
   x = 1,092,663.16/1,189.54
6. Step 6: Final answer
   x = 918.56