Finding the Third Proportional to 313.50 and 386.50

Step by Step Solution

1. Step 1: Write the proportion equation
   313.50 : 386.50 = 386.50 : x
2. Step 2: Convert to fraction form
   313.50/386.50 = 386.50/x
3. Step 3: Cross multiply
   313.50x = 386.50 × 386.50
4. Step 4: Simplify right side
   313.50x = 149,382.25
5. Step 5: Solve for x
   x = 149,382.25/313.50
6. Step 6: Final answer
   x = 476.50