Finding the Third Proportional to 10,099.50 and 20,688.50

Step by Step Solution

1. Step 1: Write the proportion equation
   10,099.50 : 20,688.50 = 20,688.50 : x
2. Step 2: Convert to fraction form
   10,099.50/20,688.50 = 20,688.50/x
3. Step 3: Cross multiply
   10,099.50x = 20,688.50 × 20,688.50
4. Step 4: Simplify right side
   10,099.50x = 428,014,032.25
5. Step 5: Solve for x
   x = 428,014,032.25/10,099.50
6. Step 6: Final answer
   x = 42,379.72