Finding the Third Proportional to 120,866 and 256,140

Step by Step Solution

1. Step 1: Write the proportion equation
   120,866 : 256,140 = 256,140 : x
2. Step 2: Convert to fraction form
   120,866/256,140 = 256,140/x
3. Step 3: Cross multiply
   120,866x = 256,140 × 256,140
4. Step 4: Simplify right side
   120,866x = 65,607,699,600
5. Step 5: Solve for x
   x = 65,607,699,600/120,866
6. Step 6: Final answer
   x = 542,813.53