Finding the Third Proportional to 20.50 and 39.69

Step by Step Solution

1. Step 1: Write the proportion equation
   20.50 : 39.69 = 39.69 : x
2. Step 2: Convert to fraction form
   20.50/39.69 = 39.69/x
3. Step 3: Cross multiply
   20.50x = 39.69 × 39.69
4. Step 4: Simplify right side
   20.50x = 1,575.10
5. Step 5: Solve for x
   x = 1,575.10/20.50
6. Step 6: Final answer
   x = 76.83