Finding the Third Proportional to 661.50 and 718.50

Step by Step Solution

1. Step 1: Write the proportion equation
   661.50 : 718.50 = 718.50 : x
2. Step 2: Convert to fraction form
   661.50/718.50 = 718.50/x
3. Step 3: Cross multiply
   661.50x = 718.50 × 718.50
4. Step 4: Simplify right side
   661.50x = 516,242.25
5. Step 5: Solve for x
   x = 516,242.25/661.50
6. Step 6: Final answer
   x = 780.41