Finding the Third Proportional to 3,947.50 and 9,139.50

Step by Step Solution

1. Step 1: Write the proportion equation
   3,947.50 : 9,139.50 = 9,139.50 : x
2. Step 2: Convert to fraction form
   3,947.50/9,139.50 = 9,139.50/x
3. Step 3: Cross multiply
   3,947.50x = 9,139.50 × 9,139.50
4. Step 4: Simplify right side
   3,947.50x = 83,530,460.25
5. Step 5: Solve for x
   x = 83,530,460.25/3,947.50
6. Step 6: Final answer
   x = 21,160.34