Finding the Fourth Proportional to 1,665.01, 2,498.96 and 639.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,665.01 : 2,498.96 = 639.73 : x
2. Step 2: Convert to fraction form
   1,665.01/2,498.96 = 639.73/x
3. Step 3: Cross multiply
   1,665.01x = 2,498.96 × 639.73
4. Step 4: Simplify right side
   1,665.01x = 1,598,659.68
5. Step 5: Solve for x
   x = 1,598,659.68/1,665.01
6. Step 6: Final answer
   x = 960.15