Finding the Fourth Proportional to 1,189.89, 1,642.05 and 665.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.89 : 1,642.05 = 665.91 : x
2. Step 2: Convert to fraction form
   1,189.89/1,642.05 = 665.91/x
3. Step 3: Cross multiply
   1,189.89x = 1,642.05 × 665.91
4. Step 4: Simplify right side
   1,189.89x = 1,093,457.52
5. Step 5: Solve for x
   x = 1,093,457.52/1,189.89
6. Step 6: Final answer
   x = 918.96