Finding the Third Proportional to 139.56 and 217.06

Step by Step Solution

1. Step 1: Write the proportion equation
   139.56 : 217.06 = 217.06 : x
2. Step 2: Convert to fraction form
   139.56/217.06 = 217.06/x
3. Step 3: Cross multiply
   139.56x = 217.06 × 217.06
4. Step 4: Simplify right side
   139.56x = 47,116.13
5. Step 5: Solve for x
   x = 47,116.13/139.56
6. Step 6: Final answer
   x = 337.60