Finding the Third Proportional to 139.88 and 315.94

Step by Step Solution

1. Step 1: Write the proportion equation
   139.88 : 315.94 = 315.94 : x
2. Step 2: Convert to fraction form
   139.88/315.94 = 315.94/x
3. Step 3: Cross multiply
   139.88x = 315.94 × 315.94
4. Step 4: Simplify right side
   139.88x = 99,816.50
5. Step 5: Solve for x
   x = 99,816.50/139.88
6. Step 6: Final answer
   x = 713.61