Finding the Third Proportional to 3,978 and 7,128

Step by Step Solution

1. Step 1: Write the proportion equation
   3,978 : 7,128 = 7,128 : x
2. Step 2: Convert to fraction form
   3,978/7,128 = 7,128/x
3. Step 3: Cross multiply
   3,978x = 7,128 × 7,128
4. Step 4: Simplify right side
   3,978x = 50,808,384
5. Step 5: Solve for x
   x = 50,808,384/3,978
6. Step 6: Final answer
   x = 12,772.34