Finding the Fourth Proportional to 1,128.50, 1,559.28 and 931.67

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.50 : 1,559.28 = 931.67 : x
2. Step 2: Convert to fraction form
   1,128.50/1,559.28 = 931.67/x
3. Step 3: Cross multiply
   1,128.50x = 1,559.28 × 931.67
4. Step 4: Simplify right side
   1,128.50x = 1,452,726.60
5. Step 5: Solve for x
   x = 1,452,726.60/1,128.50
6. Step 6: Final answer
   x = 1,287.31