Finding the Third Proportional to 9,978 and 20,790

Step by Step Solution

1. Step 1: Write the proportion equation
   9,978 : 20,790 = 20,790 : x
2. Step 2: Convert to fraction form
   9,978/20,790 = 20,790/x
3. Step 3: Cross multiply
   9,978x = 20,790 × 20,790
4. Step 4: Simplify right side
   9,978x = 432,224,100
5. Step 5: Solve for x
   x = 432,224,100/9,978
6. Step 6: Final answer
   x = 43,317.71