Finding the Third Proportional to 129,780 and 279,360

Step by Step Solution

1. Step 1: Write the proportion equation
   129,780 : 279,360 = 279,360 : x
2. Step 2: Convert to fraction form
   129,780/279,360 = 279,360/x
3. Step 3: Cross multiply
   129,780x = 279,360 × 279,360
4. Step 4: Simplify right side
   129,780x = 78,042,009,600
5. Step 5: Solve for x
   x = 78,042,009,600/129,780
6. Step 6: Final answer
   x = 601,340.80