Finding the Third Proportional to 478.50 and 721.50

Step by Step Solution

1. Step 1: Write the proportion equation
   478.50 : 721.50 = 721.50 : x
2. Step 2: Convert to fraction form
   478.50/721.50 = 721.50/x
3. Step 3: Cross multiply
   478.50x = 721.50 × 721.50
4. Step 4: Simplify right side
   478.50x = 520,562.25
5. Step 5: Solve for x
   x = 520,562.25/478.50
6. Step 6: Final answer
   x = 1,087.90