Finding the Third Proportional to 387,626 and 821,280

Step by Step Solution

1. Step 1: Write the proportion equation
   387,626 : 821,280 = 821,280 : x
2. Step 2: Convert to fraction form
   387,626/821,280 = 821,280/x
3. Step 3: Cross multiply
   387,626x = 821,280 × 821,280
4. Step 4: Simplify right side
   387,626x = 674,500,838,400
5. Step 5: Solve for x
   x = 674,500,838,400/387,626
6. Step 6: Final answer
   x = 1,740,081.52