Finding the Fourth Proportional to 3,420.15, 5,128.31 and 1,079.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,420.15 : 5,128.31 = 1,079.72 : x
2. Step 2: Convert to fraction form
   3,420.15/5,128.31 = 1,079.72/x
3. Step 3: Cross multiply
   3,420.15x = 5,128.31 × 1,079.72
4. Step 4: Simplify right side
   3,420.15x = 5,537,138.87
5. Step 5: Solve for x
   x = 5,537,138.87/3,420.15
6. Step 6: Final answer
   x = 1,618.98