Finding the Third Proportional to 139.78 and 214.73

Step by Step Solution

1. Step 1: Write the proportion equation
   139.78 : 214.73 = 214.73 : x
2. Step 2: Convert to fraction form
   139.78/214.73 = 214.73/x
3. Step 3: Cross multiply
   139.78x = 214.73 × 214.73
4. Step 4: Simplify right side
   139.78x = 46,110.85
5. Step 5: Solve for x
   x = 46,110.85/139.78
6. Step 6: Final answer
   x = 329.88