Finding the Fourth Proportional to 1,139.57, 1,712.71 and 945.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.57 : 1,712.71 = 945.81 : x
2. Step 2: Convert to fraction form
   1,139.57/1,712.71 = 945.81/x
3. Step 3: Cross multiply
   1,139.57x = 1,712.71 × 945.81
4. Step 4: Simplify right side
   1,139.57x = 1,619,899.43
5. Step 5: Solve for x
   x = 1,619,899.43/1,139.57
6. Step 6: Final answer
   x = 1,421.50