Finding the Third Proportional to 641.06 and 1,390.69

Step by Step Solution

1. Step 1: Write the proportion equation
   641.06 : 1,390.69 = 1,390.69 : x
2. Step 2: Convert to fraction form
   641.06/1,390.69 = 1,390.69/x
3. Step 3: Cross multiply
   641.06x = 1,390.69 × 1,390.69
4. Step 4: Simplify right side
   641.06x = 1,934,011.72
5. Step 5: Solve for x
   x = 1,934,011.72/641.06
6. Step 6: Final answer
   x = 3,016.88