Finding the Fourth Proportional to 1,389.98, 1,916.87 and 1,017.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.98 : 1,916.87 = 1,017.28 : x
2. Step 2: Convert to fraction form
   1,389.98/1,916.87 = 1,017.28/x
3. Step 3: Cross multiply
   1,389.98x = 1,916.87 × 1,017.28
4. Step 4: Simplify right side
   1,389.98x = 1,949,980.04
5. Step 5: Solve for x
   x = 1,949,980.04/1,389.98
6. Step 6: Final answer
   x = 1,402.89