Finding the Fourth Proportional to 1,389.29, 1,916.45 and 891.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.29 : 1,916.45 = 891.37 : x
2. Step 2: Convert to fraction form
   1,389.29/1,916.45 = 891.37/x
3. Step 3: Cross multiply
   1,389.29x = 1,916.45 × 891.37
4. Step 4: Simplify right side
   1,389.29x = 1,708,266.04
5. Step 5: Solve for x
   x = 1,708,266.04/1,389.29
6. Step 6: Final answer
   x = 1,229.60