Finding the Third Proportional to 438,390 and 685,266.75

Step by Step Solution

1. Step 1: Write the proportion equation
   438,390 : 685,266.75 = 685,266.75 : x
2. Step 2: Convert to fraction form
   438,390/685,266.75 = 685,266.75/x
3. Step 3: Cross multiply
   438,390x = 685,266.75 × 685,266.75
4. Step 4: Simplify right side
   438,390x = 469,590,518,655.56
5. Step 5: Solve for x
   x = 469,590,518,655.56/438,390
6. Step 6: Final answer
   x = 1,071,170.69