Finding the Third Proportional to 8,780 and 13,290

Step by Step Solution

1. Step 1: Write the proportion equation
   8,780 : 13,290 = 13,290 : x
2. Step 2: Convert to fraction form
   8,780/13,290 = 13,290/x
3. Step 3: Cross multiply
   8,780x = 13,290 × 13,290
4. Step 4: Simplify right side
   8,780x = 176,624,100
5. Step 5: Solve for x
   x = 176,624,100/8,780
6. Step 6: Final answer
   x = 20,116.64