Finding the Third Proportional to 278,836 and 420,870

Step by Step Solution

1. Step 1: Write the proportion equation
   278,836 : 420,870 = 420,870 : x
2. Step 2: Convert to fraction form
   278,836/420,870 = 420,870/x
3. Step 3: Cross multiply
   278,836x = 420,870 × 420,870
4. Step 4: Simplify right side
   278,836x = 177,131,556,900
5. Step 5: Solve for x
   x = 177,131,556,900/278,836
6. Step 6: Final answer
   x = 635,253.54