Finding the Third Proportional to 3,990 and 5,490

Step by Step Solution

1. Step 1: Write the proportion equation
   3,990 : 5,490 = 5,490 : x
2. Step 2: Convert to fraction form
   3,990/5,490 = 5,490/x
3. Step 3: Cross multiply
   3,990x = 5,490 × 5,490
4. Step 4: Simplify right side
   3,990x = 30,140,100
5. Step 5: Solve for x
   x = 30,140,100/3,990
6. Step 6: Final answer
   x = 7,553.91