Finding the Third Proportional to 646.31 and 1,389.38

Step by Step Solution

1. Step 1: Write the proportion equation
   646.31 : 1,389.38 = 1,389.38 : x
2. Step 2: Convert to fraction form
   646.31/1,389.38 = 1,389.38/x
3. Step 3: Cross multiply
   646.31x = 1,389.38 × 1,389.38
4. Step 4: Simplify right side
   646.31x = 1,930,362.89
5. Step 5: Solve for x
   x = 1,930,362.89/646.31
6. Step 6: Final answer
   x = 2,986.73