Finding the Fourth Proportional to 1,370.81, 1,891.61 and 839.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.81 : 1,891.61 = 839.47 : x
2. Step 2: Convert to fraction form
   1,370.81/1,891.61 = 839.47/x
3. Step 3: Cross multiply
   1,370.81x = 1,891.61 × 839.47
4. Step 4: Simplify right side
   1,370.81x = 1,587,949.85
5. Step 5: Solve for x
   x = 1,587,949.85/1,370.81
6. Step 6: Final answer
   x = 1,158.40