Finding the Fourth Proportional to 2,139.89, 3,211.65 and 842.27

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.89 : 3,211.65 = 842.27 : x
2. Step 2: Convert to fraction form
   2,139.89/3,211.65 = 842.27/x
3. Step 3: Cross multiply
   2,139.89x = 3,211.65 × 842.27
4. Step 4: Simplify right side
   2,139.89x = 2,705,076.45
5. Step 5: Solve for x
   x = 2,705,076.45/2,139.89
6. Step 6: Final answer
   x = 1,264.12