Finding the Third Proportional to 391,680 and 528,470

Step by Step Solution

1. Step 1: Write the proportion equation
   391,680 : 528,470 = 528,470 : x
2. Step 2: Convert to fraction form
   391,680/528,470 = 528,470/x
3. Step 3: Cross multiply
   391,680x = 528,470 × 528,470
4. Step 4: Simplify right side
   391,680x = 279,280,540,900
5. Step 5: Solve for x
   x = 279,280,540,900/391,680
6. Step 6: Final answer
   x = 713,032.43