Finding the Fourth Proportional to 1,280.42, 1,920.72 and 447.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.42 : 1,920.72 = 447.50 : x
2. Step 2: Convert to fraction form
   1,280.42/1,920.72 = 447.50/x
3. Step 3: Cross multiply
   1,280.42x = 1,920.72 × 447.50
4. Step 4: Simplify right side
   1,280.42x = 859,522.20
5. Step 5: Solve for x
   x = 859,522.20/1,280.42
6. Step 6: Final answer
   x = 671.28