Finding the Third Proportional to 139.54 and 209.30

Step by Step Solution

1. Step 1: Write the proportion equation
   139.54 : 209.30 = 209.30 : x
2. Step 2: Convert to fraction form
   139.54/209.30 = 209.30/x
3. Step 3: Cross multiply
   139.54x = 209.30 × 209.30
4. Step 4: Simplify right side
   139.54x = 43,807.63
5. Step 5: Solve for x
   x = 43,807.63/139.54
6. Step 6: Final answer
   x = 313.95