Finding the Fourth Proportional to 1,429.36, 1,972.16 and 839.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,429.36 : 1,972.16 = 839.78 : x
2. Step 2: Convert to fraction form
   1,429.36/1,972.16 = 839.78/x
3. Step 3: Cross multiply
   1,429.36x = 1,972.16 × 839.78
4. Step 4: Simplify right side
   1,429.36x = 1,656,180.52
5. Step 5: Solve for x
   x = 1,656,180.52/1,429.36
6. Step 6: Final answer
   x = 1,158.69