Finding the Third Proportional to 321,780 and 423,140

Step by Step Solution

1. Step 1: Write the proportion equation
   321,780 : 423,140 = 423,140 : x
2. Step 2: Convert to fraction form
   321,780/423,140 = 423,140/x
3. Step 3: Cross multiply
   321,780x = 423,140 × 423,140
4. Step 4: Simplify right side
   321,780x = 179,047,459,600
5. Step 5: Solve for x
   x = 179,047,459,600/321,780
6. Step 6: Final answer
   x = 556,428.18