Finding the Third Proportional to 639,390 and 1,378,500

Step by Step Solution

1. Step 1: Write the proportion equation
   639,390 : 1,378,500 = 1,378,500 : x
2. Step 2: Convert to fraction form
   639,390/1,378,500 = 1,378,500/x
3. Step 3: Cross multiply
   639,390x = 1,378,500 × 1,378,500
4. Step 4: Simplify right side
   639,390x = 1,900,262,250,000
5. Step 5: Solve for x
   x = 1,900,262,250,000/639,390
6. Step 6: Final answer
   x = 2,971,992.45