Finding the Third Proportional to 257,340 and 390,384

Step by Step Solution

1. Step 1: Write the proportion equation
   257,340 : 390,384 = 390,384 : x
2. Step 2: Convert to fraction form
   257,340/390,384 = 390,384/x
3. Step 3: Cross multiply
   257,340x = 390,384 × 390,384
4. Step 4: Simplify right side
   257,340x = 152,399,667,456
5. Step 5: Solve for x
   x = 152,399,667,456/257,340
6. Step 6: Final answer
   x = 592,211.34