Finding the Third Proportional to 293,074 and 638,640

Step by Step Solution

1. Step 1: Write the proportion equation
   293,074 : 638,640 = 638,640 : x
2. Step 2: Convert to fraction form
   293,074/638,640 = 638,640/x
3. Step 3: Cross multiply
   293,074x = 638,640 × 638,640
4. Step 4: Simplify right side
   293,074x = 407,861,049,600
5. Step 5: Solve for x
   x = 407,861,049,600/293,074
6. Step 6: Final answer
   x = 1,391,665.76