Finding the Third Proportional to 300,412 and 643,470

Step by Step Solution

1. Step 1: Write the proportion equation
   300,412 : 643,470 = 643,470 : x
2. Step 2: Convert to fraction form
   300,412/643,470 = 643,470/x
3. Step 3: Cross multiply
   300,412x = 643,470 × 643,470
4. Step 4: Simplify right side
   300,412x = 414,053,640,900
5. Step 5: Solve for x
   x = 414,053,640,900/300,412
6. Step 6: Final answer
   x = 1,378,285.96