Finding the Third Proportional to 278,724 and 420,697.50

Step by Step Solution

1. Step 1: Write the proportion equation
   278,724 : 420,697.50 = 420,697.50 : x
2. Step 2: Convert to fraction form
   278,724/420,697.50 = 420,697.50/x
3. Step 3: Cross multiply
   278,724x = 420,697.50 × 420,697.50
4. Step 4: Simplify right side
   278,724x = 176,986,386,506.25
5. Step 5: Solve for x
   x = 176,986,386,506.25/278,724
6. Step 6: Final answer
   x = 634,987.97