Finding the Fourth Proportional to 2,920.72, 4,381.30 and 840.71

Step by Step Solution

1. Step 1: Write the proportion equation
   2,920.72 : 4,381.30 = 840.71 : x
2. Step 2: Convert to fraction form
   2,920.72/4,381.30 = 840.71/x
3. Step 3: Cross multiply
   2,920.72x = 4,381.30 × 840.71
4. Step 4: Simplify right side
   2,920.72x = 3,683,402.72
5. Step 5: Solve for x
   x = 3,683,402.72/2,920.72
6. Step 6: Final answer
   x = 1,261.13