Finding the Third Proportional to 120,220 and 278,300

Step by Step Solution

1. Step 1: Write the proportion equation
   120,220 : 278,300 = 278,300 : x
2. Step 2: Convert to fraction form
   120,220/278,300 = 278,300/x
3. Step 3: Cross multiply
   120,220x = 278,300 × 278,300
4. Step 4: Simplify right side
   120,220x = 77,450,890,000
5. Step 5: Solve for x
   x = 77,450,890,000/120,220
6. Step 6: Final answer
   x = 644,242.97