Finding the Third Proportional to 390,057,921 and 812,400,819

Step by Step Solution

1. Step 1: Write the proportion equation
   390,057,921 : 812,400,819 = 812,400,819 : x
2. Step 2: Convert to fraction form
   390,057,921/812,400,819 = 812,400,819/x
3. Step 3: Cross multiply
   390,057,921x = 812,400,819 × 812,400,819
4. Step 4: Simplify right side
   390,057,921x = 659,995,090,711,870,720
5. Step 5: Solve for x
   x = 659,995,090,711,870,720/390,057,921
6. Step 6: Final answer
   x = 1,692,043,809.85