Finding the Third Proportional to 8,613 and 12,991.50

Step by Step Solution

1. Step 1: Write the proportion equation
   8,613 : 12,991.50 = 12,991.50 : x
2. Step 2: Convert to fraction form
   8,613/12,991.50 = 12,991.50/x
3. Step 3: Cross multiply
   8,613x = 12,991.50 × 12,991.50
4. Step 4: Simplify right side
   8,613x = 168,779,072.25
5. Step 5: Solve for x
   x = 168,779,072.25/8,613
6. Step 6: Final answer
   x = 19,595.85