Finding the Third Proportional to 640.31 and 1,375.69

Step by Step Solution

1. Step 1: Write the proportion equation
   640.31 : 1,375.69 = 1,375.69 : x
2. Step 2: Convert to fraction form
   640.31/1,375.69 = 1,375.69/x
3. Step 3: Cross multiply
   640.31x = 1,375.69 × 1,375.69
4. Step 4: Simplify right side
   640.31x = 1,892,516.10
5. Step 5: Solve for x
   x = 1,892,516.10/640.31
6. Step 6: Final answer
   x = 2,955.61