Finding the Third Proportional to 128,440 and 300,040

Step by Step Solution

1. Step 1: Write the proportion equation
   128,440 : 300,040 = 300,040 : x
2. Step 2: Convert to fraction form
   128,440/300,040 = 300,040/x
3. Step 3: Cross multiply
   128,440x = 300,040 × 300,040
4. Step 4: Simplify right side
   128,440x = 90,024,001,600
5. Step 5: Solve for x
   x = 90,024,001,600/128,440
6. Step 6: Final answer
   x = 700,903.16