Finding the Third Proportional to 718.50 and 790.50

Step by Step Solution

1. Step 1: Write the proportion equation
   718.50 : 790.50 = 790.50 : x
2. Step 2: Convert to fraction form
   718.50/790.50 = 790.50/x
3. Step 3: Cross multiply
   718.50x = 790.50 × 790.50
4. Step 4: Simplify right side
   718.50x = 624,890.25
5. Step 5: Solve for x
   x = 624,890.25/718.50
6. Step 6: Final answer
   x = 869.72