Finding the Fourth Proportional to 1,639.10, 2,261.31 and 1,079.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,639.10 : 2,261.31 = 1,079.86 : x
2. Step 2: Convert to fraction form
   1,639.10/2,261.31 = 1,079.86/x
3. Step 3: Cross multiply
   1,639.10x = 2,261.31 × 1,079.86
4. Step 4: Simplify right side
   1,639.10x = 2,441,889.86
5. Step 5: Solve for x
   x = 2,441,889.86/1,639.10
6. Step 6: Final answer
   x = 1,489.78