Finding the Third Proportional to 21,408 and 31,920

Step by Step Solution

1. Step 1: Write the proportion equation
   21,408 : 31,920 = 31,920 : x
2. Step 2: Convert to fraction form
   21,408/31,920 = 31,920/x
3. Step 3: Cross multiply
   21,408x = 31,920 × 31,920
4. Step 4: Simplify right side
   21,408x = 1,018,886,400
5. Step 5: Solve for x
   x = 1,018,886,400/21,408
6. Step 6: Final answer
   x = 47,593.72