Finding the Third Proportional to 60,720 and 128,839.50

Step by Step Solution

1. Step 1: Write the proportion equation
   60,720 : 128,839.50 = 128,839.50 : x
2. Step 2: Convert to fraction form
   60,720/128,839.50 = 128,839.50/x
3. Step 3: Cross multiply
   60,720x = 128,839.50 × 128,839.50
4. Step 4: Simplify right side
   60,720x = 16,599,616,760.25
5. Step 5: Solve for x
   x = 16,599,616,760.25/60,720
6. Step 6: Final answer
   x = 273,379.72