Finding the Third Proportional to 3,929.63 and 8,428.50

Step by Step Solution

1. Step 1: Write the proportion equation
   3,929.63 : 8,428.50 = 8,428.50 : x
2. Step 2: Convert to fraction form
   3,929.63/8,428.50 = 8,428.50/x
3. Step 3: Cross multiply
   3,929.63x = 8,428.50 × 8,428.50
4. Step 4: Simplify right side
   3,929.63x = 71,039,612.25
5. Step 5: Solve for x
   x = 71,039,612.25/3,929.63
6. Step 6: Final answer
   x = 18,077.96