Finding the Third Proportional to 139.50 and 218.63

Step by Step Solution

1. Step 1: Write the proportion equation
   139.50 : 218.63 = 218.63 : x
2. Step 2: Convert to fraction form
   139.50/218.63 = 218.63/x
3. Step 3: Cross multiply
   139.50x = 218.63 × 218.63
4. Step 4: Simplify right side
   139.50x = 47,796.89
5. Step 5: Solve for x
   x = 47,796.89/139.50
6. Step 6: Final answer
   x = 342.63