Finding the Third Proportional to 7,830 and 12,439.50

Step by Step Solution

1. Step 1: Write the proportion equation
   7,830 : 12,439.50 = 12,439.50 : x
2. Step 2: Convert to fraction form
   7,830/12,439.50 = 12,439.50/x
3. Step 3: Cross multiply
   7,830x = 12,439.50 × 12,439.50
4. Step 4: Simplify right side
   7,830x = 154,741,160.25
5. Step 5: Solve for x
   x = 154,741,160.25/7,830
6. Step 6: Final answer
   x = 19,762.60