Finding the Fourth Proportional to 1,189.59, 1,641.62 and 665.63

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.59 : 1,641.62 = 665.63 : x
2. Step 2: Convert to fraction form
   1,189.59/1,641.62 = 665.63/x
3. Step 3: Cross multiply
   1,189.59x = 1,641.62 × 665.63
4. Step 4: Simplify right side
   1,189.59x = 1,092,699.98
5. Step 5: Solve for x
   x = 1,092,699.98/1,189.59
6. Step 6: Final answer
   x = 918.55