Finding the Fourth Proportional to 1,419.18, 2,128.83 and 639.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.18 : 2,128.83 = 639.04 : x
2. Step 2: Convert to fraction form
   1,419.18/2,128.83 = 639.04/x
3. Step 3: Cross multiply
   1,419.18x = 2,128.83 × 639.04
4. Step 4: Simplify right side
   1,419.18x = 1,360,407.52
5. Step 5: Solve for x
   x = 1,360,407.52/1,419.18
6. Step 6: Final answer
   x = 958.59