Finding the Fourth Proportional to 1,189.69, 1,641.77 and 665.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.69 : 1,641.77 = 665.72 : x
2. Step 2: Convert to fraction form
   1,189.69/1,641.77 = 665.72/x
3. Step 3: Cross multiply
   1,189.69x = 1,641.77 × 665.72
4. Step 4: Simplify right side
   1,189.69x = 1,092,956.24
5. Step 5: Solve for x
   x = 1,092,956.24/1,189.69
6. Step 6: Final answer
   x = 918.69