Finding the Third Proportional to 9,978 and 21,009

Step by Step Solution

1. Step 1: Write the proportion equation
   9,978 : 21,009 = 21,009 : x
2. Step 2: Convert to fraction form
   9,978/21,009 = 21,009/x
3. Step 3: Cross multiply
   9,978x = 21,009 × 21,009
4. Step 4: Simplify right side
   9,978x = 441,378,081
5. Step 5: Solve for x
   x = 441,378,081/9,978
6. Step 6: Final answer
   x = 44,235.13