Finding the Fourth Proportional to 1,665.76, 2,498.72 and 640.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,665.76 : 2,498.72 = 640.48 : x
2. Step 2: Convert to fraction form
   1,665.76/2,498.72 = 640.48/x
3. Step 3: Cross multiply
   1,665.76x = 2,498.72 × 640.48
4. Step 4: Simplify right side
   1,665.76x = 1,600,380.19
5. Step 5: Solve for x
   x = 1,600,380.19/1,665.76
6. Step 6: Final answer
   x = 960.75