Finding the Fourth Proportional to 1,280.18, 1,917.72 and 986.66

Step by Step Solution

1. Step 1: Write the proportion equation
   1,280.18 : 1,917.72 = 986.66 : x
2. Step 2: Convert to fraction form
   1,280.18/1,917.72 = 986.66/x
3. Step 3: Cross multiply
   1,280.18x = 1,917.72 × 986.66
4. Step 4: Simplify right side
   1,280.18x = 1,892,128.03
5. Step 5: Solve for x
   x = 1,892,128.03/1,280.18
6. Step 6: Final answer
   x = 1,478.02