Finding the Fourth Proportional to 1,388.37, 1,916.27 and 891.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.37 : 1,916.27 = 891.43 : x
2. Step 2: Convert to fraction form
   1,388.37/1,916.27 = 891.43/x
3. Step 3: Cross multiply
   1,388.37x = 1,916.27 × 891.43
4. Step 4: Simplify right side
   1,388.37x = 1,708,220.57
5. Step 5: Solve for x
   x = 1,708,220.57/1,388.37
6. Step 6: Final answer
   x = 1,230.38