Finding the Third Proportional to 11,172 and 21,780

Step by Step Solution

1. Step 1: Write the proportion equation
   11,172 : 21,780 = 21,780 : x
2. Step 2: Convert to fraction form
   11,172/21,780 = 21,780/x
3. Step 3: Cross multiply
   11,172x = 21,780 × 21,780
4. Step 4: Simplify right side
   11,172x = 474,368,400
5. Step 5: Solve for x
   x = 474,368,400/11,172
6. Step 6: Final answer
   x = 42,460.47