Finding the Third Proportional to 310.25 and 388.50

Step by Step Solution

1. Step 1: Write the proportion equation
   310.25 : 388.50 = 388.50 : x
2. Step 2: Convert to fraction form
   310.25/388.50 = 388.50/x
3. Step 3: Cross multiply
   310.25x = 388.50 × 388.50
4. Step 4: Simplify right side
   310.25x = 150,932.25
5. Step 5: Solve for x
   x = 150,932.25/310.25
6. Step 6: Final answer
   x = 486.49