Finding the Third Proportional to 31.78 and 69.47

Step by Step Solution

1. Step 1: Write the proportion equation
   31.78 : 69.47 = 69.47 : x
2. Step 2: Convert to fraction form
   31.78/69.47 = 69.47/x
3. Step 3: Cross multiply
   31.78x = 69.47 × 69.47
4. Step 4: Simplify right side
   31.78x = 4,825.91
5. Step 5: Solve for x
   x = 4,825.91/31.78
6. Step 6: Final answer
   x = 151.85