Finding the Third Proportional to 1,686.76 and 3,939.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,686.76 : 3,939.89 = 3,939.89 : x
2. Step 2: Convert to fraction form
   1,686.76/3,939.89 = 3,939.89/x
3. Step 3: Cross multiply
   1,686.76x = 3,939.89 × 3,939.89
4. Step 4: Simplify right side
   1,686.76x = 15,522,738.14
5. Step 5: Solve for x
   x = 15,522,738.14/1,686.76
6. Step 6: Final answer
   x = 9,202.69