Finding the Third Proportional to 260,480 and 390,648

Step by Step Solution

1. Step 1: Write the proportion equation
   260,480 : 390,648 = 390,648 : x
2. Step 2: Convert to fraction form
   260,480/390,648 = 390,648/x
3. Step 3: Cross multiply
   260,480x = 390,648 × 390,648
4. Step 4: Simplify right side
   260,480x = 152,605,859,904
5. Step 5: Solve for x
   x = 152,605,859,904/260,480
6. Step 6: Final answer
   x = 585,864.02