Finding the Third Proportional to 289.69 and 621.56

Step by Step Solution

1. Step 1: Write the proportion equation
   289.69 : 621.56 = 621.56 : x
2. Step 2: Convert to fraction form
   289.69/621.56 = 621.56/x
3. Step 3: Cross multiply
   289.69x = 621.56 × 621.56
4. Step 4: Simplify right side
   289.69x = 386,339.94
5. Step 5: Solve for x
   x = 386,339.94/289.69
6. Step 6: Final answer
   x = 1,333.64