Finding the Third Proportional to 5,115 and 10,369.50

Step by Step Solution

1. Step 1: Write the proportion equation
   5,115 : 10,369.50 = 10,369.50 : x
2. Step 2: Convert to fraction form
   5,115/10,369.50 = 10,369.50/x
3. Step 3: Cross multiply
   5,115x = 10,369.50 × 10,369.50
4. Step 4: Simplify right side
   5,115x = 107,526,530.25
5. Step 5: Solve for x
   x = 107,526,530.25/5,115
6. Step 6: Final answer
   x = 21,021.80