Finding the Fourth Proportional to 1,311.59, 1,976.42 and 1,085.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.59 : 1,976.42 = 1,085.58 : x
2. Step 2: Convert to fraction form
   1,311.59/1,976.42 = 1,085.58/x
3. Step 3: Cross multiply
   1,311.59x = 1,976.42 × 1,085.58
4. Step 4: Simplify right side
   1,311.59x = 2,145,556.60
5. Step 5: Solve for x
   x = 2,145,556.60/1,311.59
6. Step 6: Final answer
   x = 1,635.85