Finding the Fourth Proportional to 1,370.85, 1,891.91 and 781.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.85 : 1,891.91 = 781.38 : x
2. Step 2: Convert to fraction form
   1,370.85/1,891.91 = 781.38/x
3. Step 3: Cross multiply
   1,370.85x = 1,891.91 × 781.38
4. Step 4: Simplify right side
   1,370.85x = 1,478,300.64
5. Step 5: Solve for x
   x = 1,478,300.64/1,370.85
6. Step 6: Final answer
   x = 1,078.38