Finding the Fourth Proportional to 1,188.84, 1,640.59 and 664.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.84 : 1,640.59 = 664.88 : x
2. Step 2: Convert to fraction form
   1,188.84/1,640.59 = 664.88/x
3. Step 3: Cross multiply
   1,188.84x = 1,640.59 × 664.88
4. Step 4: Simplify right side
   1,188.84x = 1,090,785.61
5. Step 5: Solve for x
   x = 1,090,785.61/1,188.84
6. Step 6: Final answer
   x = 917.52