Finding the Third Proportional to 31.80 and 69.61

Step by Step Solution

1. Step 1: Write the proportion equation
   31.80 : 69.61 = 69.61 : x
2. Step 2: Convert to fraction form
   31.80/69.61 = 69.61/x
3. Step 3: Cross multiply
   31.80x = 69.61 × 69.61
4. Step 4: Simplify right side
   31.80x = 4,845.47
5. Step 5: Solve for x
   x = 4,845.47/31.80
6. Step 6: Final answer
   x = 152.38