Finding the Third Proportional to 389 and 661.50

Step by Step Solution

1. Step 1: Write the proportion equation
   389 : 661.50 = 661.50 : x
2. Step 2: Convert to fraction form
   389/661.50 = 661.50/x
3. Step 3: Cross multiply
   389x = 661.50 × 661.50
4. Step 4: Simplify right side
   389x = 437,582.25
5. Step 5: Solve for x
   x = 437,582.25/389
6. Step 6: Final answer
   x = 1,124.89