Finding the Third Proportional to 217,920 and 326,870

Step by Step Solution

1. Step 1: Write the proportion equation
   217,920 : 326,870 = 326,870 : x
2. Step 2: Convert to fraction form
   217,920/326,870 = 326,870/x
3. Step 3: Cross multiply
   217,920x = 326,870 × 326,870
4. Step 4: Simplify right side
   217,920x = 106,843,996,900
5. Step 5: Solve for x
   x = 106,843,996,900/217,920
6. Step 6: Final answer
   x = 490,290.00