Finding the Fourth Proportional to 1,419.90, 1,959.72 and 830.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.90 : 1,959.72 = 830.40 : x
2. Step 2: Convert to fraction form
   1,419.90/1,959.72 = 830.40/x
3. Step 3: Cross multiply
   1,419.90x = 1,959.72 × 830.40
4. Step 4: Simplify right side
   1,419.90x = 1,627,351.49
5. Step 5: Solve for x
   x = 1,627,351.49/1,419.90
6. Step 6: Final answer
   x = 1,146.10