Finding the Fourth Proportional to 2,109.78, 2,911.30 and 1,225.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,109.78 : 2,911.30 = 1,225.57 : x
2. Step 2: Convert to fraction form
   2,109.78/2,911.30 = 1,225.57/x
3. Step 3: Cross multiply
   2,109.78x = 2,911.30 × 1,225.57
4. Step 4: Simplify right side
   2,109.78x = 3,568,001.94
5. Step 5: Solve for x
   x = 3,568,001.94/2,109.78
6. Step 6: Final answer
   x = 1,691.17