Finding the Fourth Proportional to 1,128.01, 1,689.24 and 931.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.01 : 1,689.24 = 931.81 : x
2. Step 2: Convert to fraction form
   1,128.01/1,689.24 = 931.81/x
3. Step 3: Cross multiply
   1,128.01x = 1,689.24 × 931.81
4. Step 4: Simplify right side
   1,128.01x = 1,574,050.72
5. Step 5: Solve for x
   x = 1,574,050.72/1,128.01
6. Step 6: Final answer
   x = 1,395.42