Finding the Third Proportional to 280.69 and 400.78

Step by Step Solution

1. Step 1: Write the proportion equation
   280.69 : 400.78 = 400.78 : x
2. Step 2: Convert to fraction form
   280.69/400.78 = 400.78/x
3. Step 3: Cross multiply
   280.69x = 400.78 × 400.78
4. Step 4: Simplify right side
   280.69x = 160,625.61
5. Step 5: Solve for x
   x = 160,625.61/280.69
6. Step 6: Final answer
   x = 572.26