Finding the Third Proportional to 12,978 and 20,275

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978 : 20,275 = 20,275 : x
2. Step 2: Convert to fraction form
   12,978/20,275 = 20,275/x
3. Step 3: Cross multiply
   12,978x = 20,275 × 20,275
4. Step 4: Simplify right side
   12,978x = 411,075,625
5. Step 5: Solve for x
   x = 411,075,625/12,978
6. Step 6: Final answer
   x = 31,674.81