Finding the Fourth Proportional to 1,370.80, 1,891.69 and 781.33

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.80 : 1,891.69 = 781.33 : x
2. Step 2: Convert to fraction form
   1,370.80/1,891.69 = 781.33/x
3. Step 3: Cross multiply
   1,370.80x = 1,891.69 × 781.33
4. Step 4: Simplify right side
   1,370.80x = 1,478,034.15
5. Step 5: Solve for x
   x = 1,478,034.15/1,370.80
6. Step 6: Final answer
   x = 1,078.23