Finding the Third Proportional to 139.50 and 315.38

Step by Step Solution

1. Step 1: Write the proportion equation
   139.50 : 315.38 = 315.38 : x
2. Step 2: Convert to fraction form
   139.50/315.38 = 315.38/x
3. Step 3: Cross multiply
   139.50x = 315.38 × 315.38
4. Step 4: Simplify right side
   139.50x = 99,461.39
5. Step 5: Solve for x
   x = 99,461.39/139.50
6. Step 6: Final answer
   x = 712.98