Finding the Fourth Proportional to 1,429.40, 1,972.17 and 839.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,429.40 : 1,972.17 = 839.72 : x
2. Step 2: Convert to fraction form
   1,429.40/1,972.17 = 839.72/x
3. Step 3: Cross multiply
   1,429.40x = 1,972.17 × 839.72
4. Step 4: Simplify right side
   1,429.40x = 1,656,060.73
5. Step 5: Solve for x
   x = 1,656,060.73/1,429.40
6. Step 6: Final answer
   x = 1,158.57