Finding the Third Proportional to 245,638 and 390,600

Step by Step Solution

1. Step 1: Write the proportion equation
   245,638 : 390,600 = 390,600 : x
2. Step 2: Convert to fraction form
   245,638/390,600 = 390,600/x
3. Step 3: Cross multiply
   245,638x = 390,600 × 390,600
4. Step 4: Simplify right side
   245,638x = 152,568,360,000
5. Step 5: Solve for x
   x = 152,568,360,000/245,638
6. Step 6: Final answer
   x = 621,110.58