Finding the Third Proportional to 295,920 and 639,139.50

Step by Step Solution

1. Step 1: Write the proportion equation
   295,920 : 639,139.50 = 639,139.50 : x
2. Step 2: Convert to fraction form
   295,920/639,139.50 = 639,139.50/x
3. Step 3: Cross multiply
   295,920x = 639,139.50 × 639,139.50
4. Step 4: Simplify right side
   295,920x = 408,499,300,460.25
5. Step 5: Solve for x
   x = 408,499,300,460.25/295,920
6. Step 6: Final answer
   x = 1,380,438.30