Finding the Fourth Proportional to 1,139.40, 1,711.17 and 1,087.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.40 : 1,711.17 = 1,087.47 : x
2. Step 2: Convert to fraction form
   1,139.40/1,711.17 = 1,087.47/x
3. Step 3: Cross multiply
   1,139.40x = 1,711.17 × 1,087.47
4. Step 4: Simplify right side
   1,139.40x = 1,860,846.04
5. Step 5: Solve for x
   x = 1,860,846.04/1,139.40
6. Step 6: Final answer
   x = 1,633.18