Finding the Third Proportional to 686,280 and 990,050

Step by Step Solution

1. Step 1: Write the proportion equation
   686,280 : 990,050 = 990,050 : x
2. Step 2: Convert to fraction form
   686,280/990,050 = 990,050/x
3. Step 3: Cross multiply
   686,280x = 990,050 × 990,050
4. Step 4: Simplify right side
   686,280x = 980,199,002,500
5. Step 5: Solve for x
   x = 980,199,002,500/686,280
6. Step 6: Final answer
   x = 1,428,278.55