Finding the Fourth Proportional to 1,189.47, 1,641.29 and 665.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.47 : 1,641.29 = 665.40 : x
2. Step 2: Convert to fraction form
   1,189.47/1,641.29 = 665.40/x
3. Step 3: Cross multiply
   1,189.47x = 1,641.29 × 665.40
4. Step 4: Simplify right side
   1,189.47x = 1,092,111.04
5. Step 5: Solve for x
   x = 1,092,111.04/1,189.47
6. Step 6: Final answer
   x = 918.15