Finding the Third Proportional to 139.22 and 216.45

Step by Step Solution

1. Step 1: Write the proportion equation
   139.22 : 216.45 = 216.45 : x
2. Step 2: Convert to fraction form
   139.22/216.45 = 216.45/x
3. Step 3: Cross multiply
   139.22x = 216.45 × 216.45
4. Step 4: Simplify right side
   139.22x = 46,848.57
5. Step 5: Solve for x
   x = 46,848.57/139.22
6. Step 6: Final answer
   x = 336.51