Finding the Third Proportional to 8,688 and 13,090.50

Step by Step Solution

1. Step 1: Write the proportion equation
   8,688 : 13,090.50 = 13,090.50 : x
2. Step 2: Convert to fraction form
   8,688/13,090.50 = 13,090.50/x
3. Step 3: Cross multiply
   8,688x = 13,090.50 × 13,090.50
4. Step 4: Simplify right side
   8,688x = 171,361,190.25
5. Step 5: Solve for x
   x = 171,361,190.25/8,688
6. Step 6: Final answer
   x = 19,723.89