Finding the Third Proportional to 15,720 and 21,060

Step by Step Solution

1. Step 1: Write the proportion equation
   15,720 : 21,060 = 21,060 : x
2. Step 2: Convert to fraction form
   15,720/21,060 = 21,060/x
3. Step 3: Cross multiply
   15,720x = 21,060 × 21,060
4. Step 4: Simplify right side
   15,720x = 443,523,600
5. Step 5: Solve for x
   x = 443,523,600/15,720
6. Step 6: Final answer
   x = 28,213.97