Finding the Third Proportional to 30,978 and 39,987

Step by Step Solution

1. Step 1: Write the proportion equation
   30,978 : 39,987 = 39,987 : x
2. Step 2: Convert to fraction form
   30,978/39,987 = 39,987/x
3. Step 3: Cross multiply
   30,978x = 39,987 × 39,987
4. Step 4: Simplify right side
   30,978x = 1,598,960,169
5. Step 5: Solve for x
   x = 1,598,960,169/30,978
6. Step 6: Final answer
   x = 51,615.99