Finding the Third Proportional to 139.92 and 209.53

Step by Step Solution

1. Step 1: Write the proportion equation
   139.92 : 209.53 = 209.53 : x
2. Step 2: Convert to fraction form
   139.92/209.53 = 209.53/x
3. Step 3: Cross multiply
   139.92x = 209.53 × 209.53
4. Step 4: Simplify right side
   139.92x = 43,903.34
5. Step 5: Solve for x
   x = 43,903.34/139.92
6. Step 6: Final answer
   x = 313.77