Finding the Fourth Proportional to 2,070.72, 2,857.80 and 1,139.28

Step by Step Solution

1. Step 1: Write the proportion equation
   2,070.72 : 2,857.80 = 1,139.28 : x
2. Step 2: Convert to fraction form
   2,070.72/2,857.80 = 1,139.28/x
3. Step 3: Cross multiply
   2,070.72x = 2,857.80 × 1,139.28
4. Step 4: Simplify right side
   2,070.72x = 3,255,834.38
5. Step 5: Solve for x
   x = 3,255,834.38/2,070.72
6. Step 6: Final answer
   x = 1,572.32