Finding the Third Proportional to 309.38 and 478.69

Step by Step Solution

1. Step 1: Write the proportion equation
   309.38 : 478.69 = 478.69 : x
2. Step 2: Convert to fraction form
   309.38/478.69 = 478.69/x
3. Step 3: Cross multiply
   309.38x = 478.69 × 478.69
4. Step 4: Simplify right side
   309.38x = 229,141.72
5. Step 5: Solve for x
   x = 229,141.72/309.38
6. Step 6: Final answer
   x = 740.66