Finding the Third Proportional to 13,490 and 20,478

Step by Step Solution

1. Step 1: Write the proportion equation
   13,490 : 20,478 = 20,478 : x
2. Step 2: Convert to fraction form
   13,490/20,478 = 20,478/x
3. Step 3: Cross multiply
   13,490x = 20,478 × 20,478
4. Step 4: Simplify right side
   13,490x = 419,348,484
5. Step 5: Solve for x
   x = 419,348,484/13,490
6. Step 6: Final answer
   x = 31,085.88