Finding the Third Proportional to 678,438 and 921,378.38

Step by Step Solution

1. Step 1: Write the proportion equation
   678,438 : 921,378.38 = 921,378.38 : x
2. Step 2: Convert to fraction form
   678,438/921,378.38 = 921,378.38/x
3. Step 3: Cross multiply
   678,438x = 921,378.38 × 921,378.38
4. Step 4: Simplify right side
   678,438x = 848,938,109,917.64
5. Step 5: Solve for x
   x = 848,938,109,917.64/678,438
6. Step 6: Final answer
   x = 1,251,312.74