Finding the Fourth Proportional to 1,188.83, 1,640.61 and 664.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.83 : 1,640.61 = 664.82 : x
2. Step 2: Convert to fraction form
   1,188.83/1,640.61 = 664.82/x
3. Step 3: Cross multiply
   1,188.83x = 1,640.61 × 664.82
4. Step 4: Simplify right side
   1,188.83x = 1,090,710.34
5. Step 5: Solve for x
   x = 1,090,710.34/1,188.83
6. Step 6: Final answer
   x = 917.47