Finding the Third Proportional to 13,860 and 21,780

Step by Step Solution

1. Step 1: Write the proportion equation
   13,860 : 21,780 = 21,780 : x
2. Step 2: Convert to fraction form
   13,860/21,780 = 21,780/x
3. Step 3: Cross multiply
   13,860x = 21,780 × 21,780
4. Step 4: Simplify right side
   13,860x = 474,368,400
5. Step 5: Solve for x
   x = 474,368,400/13,860
6. Step 6: Final answer
   x = 34,225.71