Finding the Fourth Proportional to 2,617.60, 3,929.28 and 1,318.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,617.60 : 3,929.28 = 1,318.72 : x
2. Step 2: Convert to fraction form
   2,617.60/3,929.28 = 1,318.72/x
3. Step 3: Cross multiply
   2,617.60x = 3,929.28 × 1,318.72
4. Step 4: Simplify right side
   2,617.60x = 5,181,620.12
5. Step 5: Solve for x
   x = 5,181,620.12/2,617.60
6. Step 6: Final answer
   x = 1,979.53