Finding the Third Proportional to 421,152 and 687,630

Step by Step Solution

1. Step 1: Write the proportion equation
   421,152 : 687,630 = 687,630 : x
2. Step 2: Convert to fraction form
   421,152/687,630 = 687,630/x
3. Step 3: Cross multiply
   421,152x = 687,630 × 687,630
4. Step 4: Simplify right side
   421,152x = 472,835,016,900
5. Step 5: Solve for x
   x = 472,835,016,900/421,152
6. Step 6: Final answer
   x = 1,122,718.20