Finding the Third Proportional to 261,117 and 390,684

Step by Step Solution

1. Step 1: Write the proportion equation
   261,117 : 390,684 = 390,684 : x
2. Step 2: Convert to fraction form
   261,117/390,684 = 390,684/x
3. Step 3: Cross multiply
   261,117x = 390,684 × 390,684
4. Step 4: Simplify right side
   261,117x = 152,633,987,856
5. Step 5: Solve for x
   x = 152,633,987,856/261,117
6. Step 6: Final answer
   x = 584,542.51