Finding the Fourth Proportional to 1,028.07, 1,534.89 and 931.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,028.07 : 1,534.89 = 931.21 : x
2. Step 2: Convert to fraction form
   1,028.07/1,534.89 = 931.21/x
3. Step 3: Cross multiply
   1,028.07x = 1,534.89 × 931.21
4. Step 4: Simplify right side
   1,028.07x = 1,429,292.59
5. Step 5: Solve for x
   x = 1,429,292.59/1,028.07
6. Step 6: Final answer
   x = 1,390.27