Finding the Third Proportional to 15,390 and 17,820

Step by Step Solution

1. Step 1: Write the proportion equation
   15,390 : 17,820 = 17,820 : x
2. Step 2: Convert to fraction form
   15,390/17,820 = 17,820/x
3. Step 3: Cross multiply
   15,390x = 17,820 × 17,820
4. Step 4: Simplify right side
   15,390x = 317,552,400
5. Step 5: Solve for x
   x = 317,552,400/15,390
6. Step 6: Final answer
   x = 20,633.68