Finding the Third Proportional to 31.78 and 67.78

Step by Step Solution

1. Step 1: Write the proportion equation
   31.78 : 67.78 = 67.78 : x
2. Step 2: Convert to fraction form
   31.78/67.78 = 67.78/x
3. Step 3: Cross multiply
   31.78x = 67.78 × 67.78
4. Step 4: Simplify right side
   31.78x = 4,594.30
5. Step 5: Solve for x
   x = 4,594.30/31.78
6. Step 6: Final answer
   x = 144.56