Finding the Third Proportional to 8,139 and 9,142.50

Step by Step Solution

1. Step 1: Write the proportion equation
   8,139 : 9,142.50 = 9,142.50 : x
2. Step 2: Convert to fraction form
   8,139/9,142.50 = 9,142.50/x
3. Step 3: Cross multiply
   8,139x = 9,142.50 × 9,142.50
4. Step 4: Simplify right side
   8,139x = 83,585,306.25
5. Step 5: Solve for x
   x = 83,585,306.25/8,139
6. Step 6: Final answer
   x = 10,269.73