Finding the Fourth Proportional to 2,919.72, 4,379.80 and 839.71

Step by Step Solution

1. Step 1: Write the proportion equation
   2,919.72 : 4,379.80 = 839.71 : x
2. Step 2: Convert to fraction form
   2,919.72/4,379.80 = 839.71/x
3. Step 3: Cross multiply
   2,919.72x = 4,379.80 × 839.71
4. Step 4: Simplify right side
   2,919.72x = 3,677,761.86
5. Step 5: Solve for x
   x = 3,677,761.86/2,919.72
6. Step 6: Final answer
   x = 1,259.63