Finding the Fourth Proportional to 2,071.78, 3,107.59 and 839.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,071.78 : 3,107.59 = 839.20 : x
2. Step 2: Convert to fraction form
   2,071.78/3,107.59 = 839.20/x
3. Step 3: Cross multiply
   2,071.78x = 3,107.59 × 839.20
4. Step 4: Simplify right side
   2,071.78x = 2,607,885.33
5. Step 5: Solve for x
   x = 2,607,885.33/2,071.78
6. Step 6: Final answer
   x = 1,258.77