Finding the Third Proportional to 668,405 and 1,391,890

Step by Step Solution

1. Step 1: Write the proportion equation
   668,405 : 1,391,890 = 1,391,890 : x
2. Step 2: Convert to fraction form
   668,405/1,391,890 = 1,391,890/x
3. Step 3: Cross multiply
   668,405x = 1,391,890 × 1,391,890
4. Step 4: Simplify right side
   668,405x = 1,937,357,772,100
5. Step 5: Solve for x
   x = 1,937,357,772,100/668,405
6. Step 6: Final answer
   x = 2,898,478.87