Finding the Third Proportional to 298,910 and 645,040

Step by Step Solution

1. Step 1: Write the proportion equation
   298,910 : 645,040 = 645,040 : x
2. Step 2: Convert to fraction form
   298,910/645,040 = 645,040/x
3. Step 3: Cross multiply
   298,910x = 645,040 × 645,040
4. Step 4: Simplify right side
   298,910x = 416,076,601,600
5. Step 5: Solve for x
   x = 416,076,601,600/298,910
6. Step 6: Final answer
   x = 1,391,979.53