Finding the Third Proportional to 243,145 and 390,666

Step by Step Solution

1. Step 1: Write the proportion equation
   243,145 : 390,666 = 390,666 : x
2. Step 2: Convert to fraction form
   243,145/390,666 = 390,666/x
3. Step 3: Cross multiply
   243,145x = 390,666 × 390,666
4. Step 4: Simplify right side
   243,145x = 152,619,923,556
5. Step 5: Solve for x
   x = 152,619,923,556/243,145
6. Step 6: Final answer
   x = 627,690.98