Finding the Third Proportional to 139.50 and 214.31

Step by Step Solution

1. Step 1: Write the proportion equation
   139.50 : 214.31 = 214.31 : x
2. Step 2: Convert to fraction form
   139.50/214.31 = 214.31/x
3. Step 3: Cross multiply
   139.50x = 214.31 × 214.31
4. Step 4: Simplify right side
   139.50x = 45,929.85
5. Step 5: Solve for x
   x = 45,929.85/139.50
6. Step 6: Final answer
   x = 329.25