Finding the Third Proportional to 50.91 and 78.61

Step by Step Solution

1. Step 1: Write the proportion equation
   50.91 : 78.61 = 78.61 : x
2. Step 2: Convert to fraction form
   50.91/78.61 = 78.61/x
3. Step 3: Cross multiply
   50.91x = 78.61 × 78.61
4. Step 4: Simplify right side
   50.91x = 6,179.43
5. Step 5: Solve for x
   x = 6,179.43/50.91
6. Step 6: Final answer
   x = 121.39