Finding the Fourth Proportional to 1,280.72, 1,919.50 and 664.07

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.72 : 1,919.50 = 664.07 : x
2. Step 2: Convert to fraction form
   1,280.72/1,919.50 = 664.07/x
3. Step 3: Cross multiply
   1,280.72x = 1,919.50 × 664.07
4. Step 4: Simplify right side
   1,280.72x = 1,274,682.37
5. Step 5: Solve for x
   x = 1,274,682.37/1,280.72
6. Step 6: Final answer
   x = 995.29