Finding the Third Proportional to 397.50 and 715.50

Step by Step Solution

1. Step 1: Write the proportion equation
   397.50 : 715.50 = 715.50 : x
2. Step 2: Convert to fraction form
   397.50/715.50 = 715.50/x
3. Step 3: Cross multiply
   397.50x = 715.50 × 715.50
4. Step 4: Simplify right side
   397.50x = 511,940.25
5. Step 5: Solve for x
   x = 511,940.25/397.50
6. Step 6: Final answer
   x = 1,287.90