Finding the Third Proportional to 5,128.50 and 7,909.50

Step by Step Solution

1. Step 1: Write the proportion equation
   5,128.50 : 7,909.50 = 7,909.50 : x
2. Step 2: Convert to fraction form
   5,128.50/7,909.50 = 7,909.50/x
3. Step 3: Cross multiply
   5,128.50x = 7,909.50 × 7,909.50
4. Step 4: Simplify right side
   5,128.50x = 62,560,190.25
5. Step 5: Solve for x
   x = 62,560,190.25/5,128.50
6. Step 6: Final answer
   x = 12,198.54