Finding the Third Proportional to 298,721 and 645,142

Step by Step Solution

1. Step 1: Write the proportion equation
   298,721 : 645,142 = 645,142 : x
2. Step 2: Convert to fraction form
   298,721/645,142 = 645,142/x
3. Step 3: Cross multiply
   298,721x = 645,142 × 645,142
4. Step 4: Simplify right side
   298,721x = 416,208,200,164
5. Step 5: Solve for x
   x = 416,208,200,164/298,721
6. Step 6: Final answer
   x = 1,393,300.77