Finding the Third Proportional to 688.50 and 877.50

Step by Step Solution

1. Step 1: Write the proportion equation
   688.50 : 877.50 = 877.50 : x
2. Step 2: Convert to fraction form
   688.50/877.50 = 877.50/x
3. Step 3: Cross multiply
   688.50x = 877.50 × 877.50
4. Step 4: Simplify right side
   688.50x = 770,006.25
5. Step 5: Solve for x
   x = 770,006.25/688.50
6. Step 6: Final answer
   x = 1,118.38