Finding the Fourth Proportional to 1,189.72, 1,641.83 and 665.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.72 : 1,641.83 = 665.75 : x
2. Step 2: Convert to fraction form
   1,189.72/1,641.83 = 665.75/x
3. Step 3: Cross multiply
   1,189.72x = 1,641.83 × 665.75
4. Step 4: Simplify right side
   1,189.72x = 1,093,048.32
5. Step 5: Solve for x
   x = 1,093,048.32/1,189.72
6. Step 6: Final answer
   x = 918.74