Finding the Third Proportional to 120,390 and 259,280

Step by Step Solution

1. Step 1: Write the proportion equation
   120,390 : 259,280 = 259,280 : x
2. Step 2: Convert to fraction form
   120,390/259,280 = 259,280/x
3. Step 3: Cross multiply
   120,390x = 259,280 × 259,280
4. Step 4: Simplify right side
   120,390x = 67,226,118,400
5. Step 5: Solve for x
   x = 67,226,118,400/120,390
6. Step 6: Final answer
   x = 558,402.84