Finding the Third Proportional to 19.69 and 39.38

Step by Step Solution

1. Step 1: Write the proportion equation
   19.69 : 39.38 = 39.38 : x
2. Step 2: Convert to fraction form
   19.69/39.38 = 39.38/x
3. Step 3: Cross multiply
   19.69x = 39.38 × 39.38
4. Step 4: Simplify right side
   19.69x = 1,550.39
5. Step 5: Solve for x
   x = 1,550.39/19.69
6. Step 6: Final answer
   x = 78.75