Finding the Third Proportional to 12,990 and 18,998.50

Step by Step Solution

1. Step 1: Write the proportion equation
   12,990 : 18,998.50 = 18,998.50 : x
2. Step 2: Convert to fraction form
   12,990/18,998.50 = 18,998.50/x
3. Step 3: Cross multiply
   12,990x = 18,998.50 × 18,998.50
4. Step 4: Simplify right side
   12,990x = 360,943,002.25
5. Step 5: Solve for x
   x = 360,943,002.25/12,990
6. Step 6: Final answer
   x = 27,786.22