Finding the Third Proportional to 647.72 and 1,398.38

Step by Step Solution

1. Step 1: Write the proportion equation
   647.72 : 1,398.38 = 1,398.38 : x
2. Step 2: Convert to fraction form
   647.72/1,398.38 = 1,398.38/x
3. Step 3: Cross multiply
   647.72x = 1,398.38 × 1,398.38
4. Step 4: Simplify right side
   647.72x = 1,955,452.64
5. Step 5: Solve for x
   x = 1,955,452.64/647.72
6. Step 6: Final answer
   x = 3,018.98