Finding the Fourth Proportional to 2,570.78, 3,547.67 and 1,391.85

Step by Step Solution

1. Step 1: Write the proportion equation
   2,570.78 : 3,547.67 = 1,391.85 : x
2. Step 2: Convert to fraction form
   2,570.78/3,547.67 = 1,391.85/x
3. Step 3: Cross multiply
   2,570.78x = 3,547.67 × 1,391.85
4. Step 4: Simplify right side
   2,570.78x = 4,937,829.27
5. Step 5: Solve for x
   x = 4,937,829.27/2,570.78
6. Step 6: Final answer
   x = 1,920.75